Which are the best in history? This is a question as old as sport itself. Whether it's asked about players, coaches, teams or dynasties, it always makes for an interesting debate.

In the NFL, it's difficult to break down the greatest of all time because there have been so many vastly different eras. From the early days of football to the passing renaissance of the 1980s to the free-agency era of the '90s and onward, the league has undergone several dramatic changes.

This century has marked its own era of sorts, as it's sometimes felt like the New England Patriots and then everybody else. The Patriots have won six Super Bowls since 2001 and have appeared in nine of them. But are all of the best teams from the last 20 years Patriots teams?

As a fun exercise, we're going to break down the top 10 teams of the past decade based on how they might perform against one another in a tournament setting. Regular-season record and playoff dominance will play roles—coincidentally, every team listed had four losses or fewer (playoffs included).

But those factors won't be everything. Otherwise, this would probably just be a list of the top 10 Super Bowl champions of this century.

Team chemistry, coaching and regular-season prowess on offense and defense were also considered. Teams will be viewed as if they are 100 percent healthy. This is obviously hypothetical, so let's dig in and have some fun!

Honorable Mentions

Teams that just missed the cut include:

2004 New England Patriots

The third of New England's Super Bowl teams was arguably the best of the early dynasty. Tom Brady was beginning to develop into the elite passer he is today, while the defense allowed the second-fewest points in the league. This squad, however, wasn't quite as good as two of the franchise's later incarnations.

2006 Indianapolis Colts

Peyton Manning won his first Super Bowl with the 2006 Colts, an offensive juggernaut of a team that benefited from a swarming pass rush led by Robert Mathis and Dwight Freeney. The league's 23rd-ranked scoring defense and an underwhelming Super Bowl opponent—the Rex Grossman-led Chicago Bears—keep Indy off the list proper. The '05 and '07 Colts were arguably more dominant than the '06 iteration, but their early playoff exits could not be ignored.

2008 Pittsburgh Steelers

The 2008 Pittsburgh Steelers had a tremendous defense, ranking first in points and yards allowed. They also went 12-4 during the regular season and squeaked past the Arizona Cardinals in Super Bowl XLIII. However, Pittsburgh ranked just 22nd in total offense and sent a mere three players—James Harrison, James Farrior and Troy Polamalu—to the Pro Bowl. Quarterback Ben Roethlisberger also had one of the more pedestrian seasons of his career, throwing for 17 touchdowns with 15 interceptions.

2015 Carolina Panthers

The 2015 Carolina Panthers achieved a 15-1 regular-season record thanks to MVP Cam Newton and the league's second-ranked rushing attack. And unlike the other 15-1 teams in the last 20 years—the 2011 Packers and 2004 Steelers, who were considered for this list—Carolina made the Super Bowl. Unfortunately, the Panthers had a questionable offensive tackle duo in Michael Oher and Mike Remmers, which led to their 24-10 shellacking in Super Bowl 50.

2015 Denver Broncos

The Broncos team that beat Carolina had one of this century's best defenses. Led by Von Miller and DeMarcus Ware, the unit ranked fourth in scoring defense and first in yards allowed. However, Denver also featured the ghost of an aging Peyton Manning at quarterback and a lackluster overall offense. The 2015 Broncos bested the Panthers, but they could struggle against teams in the top 10. The 2013 Broncos—led by Manning and his 55 TD passes—were also considered, but their performance in Super Bowl XLVIII significantly hurt their cause.  

10. 2019 San Francisco 49ers

Don't blame recency bias for the 2019 San Francisco 49ers making this list. San Francisco was a dominant team last season that likely would have walked away with the Lombardi if it hadn't been up against Patrick Mahomes and the Kansas City Chiefs.

The 2019 49ers featured a rugged yet electric rushing attack led by Raheem Mostert, Matt Breida and Tevin Coleman. Creative play-calling from Kyle Shanahan made the run game hum. Only the Baltimore Ravens amassed more rushing yards in the regular season, and they had 1,206 rushing yards from quarterback Lamar Jackson. And while the passing game wasn't exactly elite, it did rank 13th in the NFL in yards—so this wasn't a lopsided offense.

Defensively, the 49ers were amazing. They ranked second in yards allowed and featured a pass rush that would give Mount Rushmore fits in the trenches. Between Nick Bosa, DeForest Buckner, Dee Ford and Arik Armstead, San Francisco had the weapons to attack any offensive line from the past 20 years.

The big drawback here is the fact that quarterback Jimmy Garoppolo is still relatively inexperienced as a starter. He has just 26 regular-season starts under his belt. Garoppolo would have trouble outdueling Tom Brady, Kurt Warner and others on this list. 

9. 2009 New Orleans Saints

There's a lot to be said about the relationship between a head coach and his quarterback. This relationship is largely why New England experienced sustained success for so long, and it's why the 2009 New Orleans Saints would be a tough out for any opponent.

Future Hall of Famer Drew Brees and head coach Sean Payton were in complete rhythm during the 2009 season, as the Saints finished ranked first in both yards (403.8) and points (31.9) per game.

New Orleans also ranked sixth in rushing behind the ball-carrying of Mike Bell, Pierre Thomas and Reggie Bush.

While New Orleans' 20th-ranked scoring defense didn't outright smother opponents, it was opportunistic, amassing 26 interceptions during the regular season.

Brees and Co. would be able to match points with any team on this list, while timely takeaways and special teams plays—like the surprise onside kick against the Colts in Super Bowl XLIV—would help compensate for a good-not-great defense.

8. 2002 Tampa Bay Buccaneers

The 2002 Tampa Bay Buccaneers are not the most balanced team on this list, but they would hold their own against most great teams of this century because of their all-time-great defense. The Bucs finished the regular season ranked first in points allowed (12.3) and yards allowed (252.8) per game.

The vaunted Tampa defense featured five All-Pro selections—Simeon Rice, Warren Sapp, Derrick Brooks, Ronde Barber and John Lynch. Sapp and Brooks are already in the Hall of Fame.

The Buccaneers offense, while clearly overshadowed by the defense, wasn't a liability. With quarterback Brad Johnson and running backs Michael Pittman Jr and Mike Alstott, the Buccaneers ranked a respectable 18th in points scored.

What earns the 2002 Bucs a spot in the top 10, however, is the way they roughed up the competition in the postseason. Tampa won its three playoff games—including Super Bowl XXXVII—by a combined score of 106-37. With an experienced coach in Jon Gruden, this squad should rise to the level of competition a hypothetical best-team tournament would provide.

7. 2001 St. Louis Rams

Next up, we have the "Greatest Show on Turf." Long before the Rams moved back to Los Angeles, they were the pride of St. Louis and one of the best offensive teams of all time. While the 2001 Rams didn't win the Super Bowl as the 1999 incarnation did, they would be a tough match for any team in the past 20 years.

Led by Hall of Fame quarterback Kurt Warner, the 2001 Rams featured one of the most prolific offenses in league history. With weapons Marshall Faulk, Torry Holt, Az-Zahir Hakeem and Isaac Bruce at his disposal, Warner would have little trouble matching points with the likes of Patrick Mahomes and Tom Brady.

St. Louis boasted the league's top scoring offense in 2001—a unit that racked up 503 points in the regular season. However, the Rams also boasted a defense that allowed the seventh-fewest points and third-fewest yards in the league.

Coaching is perhaps the biggest downfall of this well-balanced powerhouse. Mike Martz was an offensive guru but had limited success as a head coach, compiling a 3-4 playoff record with the Rams. 

6. 2017 Philadelphia Eagles

Why are the 2017 Philadelphia Eagles ranked higher than the Greatest Show on Turf? Quite simply, it's because they were talented enough to best the mighty Patriots in Super Bowl LII with backup quarterback Nick Foles at the helm.

While Foles deserves a ton of credit for leading Philadelphia's magical playoff run, a healthy Carson Wentz would lead this squad into a tournament-style setting—and Wentz was remarkable in 2017. Before he suffered a torn ACL, he passed for 3,296 yards, 33 touchdowns and just seven interceptions. He also added 299 rushing yards.

As a team, these Eagles were one of the most balanced teams in recent memory. They ranked seventh in total offense, third in scoring, fourth in overall defense and fourth in points allowed.

While it's far too early to call head coach Doug Pederson an all-time-great coach, he has produced a 42-28 record (including playoffs) and outmaneuvered the venerated Bill Belichick in this season's most important game.

5. 2000 Baltimore Ravens

Defense wins championships, and the 2000 Baltimore Ravens were living proof. This squad decimated opponents with a collective defensive force that would rival the 1985 Chicago Bears'. As a team, Baltimore allowed just 10.3 points per game in the regular season while pitching four shutouts.

With Ray Lewis, Rod Woodson, Tony Siragusa, Chris McAlister, Sam Adams and Peter Boulware on the defensive side of the ball, this squad would have a chance against anyone.

The problem, of course, is that the 2000 Ravens were quarterbacked by Trent Dilfer, one of the most underwhelming Super Bowl signal-callers of all time. He passed for a mere 1,502 yards in 11 regular-season games (eight starts) and was let go the following offseason.

These Ravens would have to lean on their defense and the running of Jamal Lewis—who amassed 1,364 yards in 2000—to win games. Given the potency of the defense, that's a formula that would work against most teams, but perhaps not the top four in our rankings.

4. 2007 New England Patriots

No, the 2007 Patriots did not win the Super Bowl. However, they well may have if not for an otherworldly connection from Eli Manning to David Tyree, and they were good enough to match up with anyone on this list.

The Patriots didn't go 16-0 during the regular season in 2007 by accident. Led by Brady, wideout Randy Moss, tight end Benjamin Watson and tackle Matt Light, these Patriots had one of the most prolific offenses in league history.

New England averaged 36.8 points per game during the regular season, while Brady and Moss connected for a whopping 23 touchdown passes. While some more modern offenses would be able to keep up, this version of New England would win a shootout in most instances.

These Patriots weren't just an offensive powerhouse, though. They ranked fourth in both yards and points allowed during the regular season and had an impressive nine players named as All-Pros.

With Bill Belichick running the show, very few teams would take out the 2007 Patriots in an elimination game.

3. 2019 Kansas City Chiefs

The 2019 Chiefs were able to outlast the 49ers in Super Bowl LIV thanks to the magic of Mahomes. That magic would help lift the Chiefs over most great teams of the past two decades.

The former Texas Tech standout has already put a league MVP and a Super Bowl MVP on his resume in just two seasons as a starter. He does things from the pocket and on the run that other quarterbacks could only dream of, and he proved during the 2019 postseason that he has the calm under pressure needed to face adversity.

The Chiefs had to overcome double-digit deficits in all three of their postseason games, and they delivered. While Mahomes deserves a ton of credit for this remarkable feat, this team wasn't about only one player. With Pro Bowlers like Tyreek Hill, Frank Clark, Chris Jones and Travis Kelce also on the roster, the 2019 Chiefs were a surprisingly balanced outfit.

Kansas City ranked fifth in scoring and fifth in passing offense, but it also ranked eighth in passing defense and seventh in points allowed. With a ferocious pass rush—one that amassed 45 sacks during the regular season—the Chiefs could go head-to-head with anyone in a quarterback battle.

This team also gets a boost from the presence of future Hall of Fame head coach Andy Reid, who owns a 222-142-1 record (including playoffs).

2. 2013 Seattle Seahawks

One quarterback who might be able to out-magic Mahomes is Seattle Seahawks signal-caller Russell Wilson. A future Hall of Famer, Wilson has amassed 21 fourth-quarter comebacks in his career and has an incredible 227-to-68 touchdown-to-interception ratio in the regular season.

With Wilson leading the offense, the 2013 Seahawks were one of the most dominant teams ever. Their defense—the fabled "Legion of Boom"—ensured that they didn't need much magic from Wilson during the run to Super Bowl XLVIII.

Led by the likes of Richard Sherman, Kam Chancellor, Earl Thomas and Bobby Wagner, the Legion was capable of thwarting even the most prolific of offenses—as it proved during a 43-8 rout of Denver in the Super Bowl.

With Wilson and a prime Marshawn Lynch on offense and returner Percy Harvin on special teams, this squad wouldn't have to rely solely on its defense to win games in a tournament setting—but it certainly could.

Head coach Pete Carroll, who has a 144-99-1 career record (playoffs included), would help ensure that Seattle would come out on top against most teams. However, as he proved during Super Bowl XLIX, he might have a problem trying to outsmart Belichick, which leads us to...

1. 2016 New England Patriots

28-3. This number signifies the resiliency and drive of the 2016 Patriots. This team went 14-2 in the regular season, boasted the league's No. 3 scoring offense, No. 1 scoring defense and had seven players named as first- or second-team All-Pros. Yet the greatness of the 2016 Patriots presented itself when they came back from a 25-point deficit against the Atlanta Falcons in Super Bowl LI.

Brady, of course, has long been known for his drive and will to win.

"I've never been around somebody in the huddle where you just knew—you just knew there was no way we were gonna lose," former Patriots guard Damien Woody said, per ESPN's Jenna Laine.

With a healthy Rob Gronkowski at tight end, the Patriots probably wouldn't have gotten that far behind, and we're assuming Gronk is healthy here. With him in the lineup, this team is one of the most balanced of the past two decades. 

On top of raw talent, experience would help lead this squad to the top of a tournament of the 21st century's best. Belichick and Brady were at the height of their mental powers when they won Lombardi No. 5. Even if they got behind against one of the other nine teams listed here, it's virtually impossible to see them not mounting a comeback.