Superstars like J.J. Watt and Ndamukong Suh pushed their units far up this list, but our defensive line rankings ultimately come down to the team the deepest group of pass rushers and run-stoppers in the NFL.

Ahead of the 2015 season, SI.com is ranking the NFL's best at every position. After ranking the league's top 10 offensive lines, wide receivers, running backs and quarterbacks, we turn our attention to the NFL's 10 best defensive lines.

Note: This top 10 is for defensive lines. So, if you're looking at this list and wondering where the Chiefs are because Justin Houston is so great (which he is), Justin Houston is an outside linebacker. He'll be on tomorrow's list covering the league's best linebackers.

1. St. Louis Rams: Say what you will about how the Rams have assembled their offensive linemen, receivers and quarterbacks during the Jeff Fisher era; nobody can say Fisher hasn't put together a formidable, intimidating defensive line. The star here is right defensive end Robert Quinn, who may be the most physically gifted outside pass rusher in the league. Few can match Quinn's speed around the edge and power when he gets home. Quinn has two 10.5-sack seasons in the last three years, with that amazing 19-sack performance in 2013 in the middle. Left defensive end Chris Long is the leader of the line and the regulator against the run—he's the strong-side force.

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St. Louis selected defensive tackle Aaron Donald out of Pitt with the 13th pick in the 2014 draft, and Donald immediately made himself a force at the NFL level. At 6'1" and 285 pounds, Donald brings an impressive power/speed combination that makes him very difficult to block. The AP Defensive Rookie of the Year finished his inaugural NFL campaign with nine sacks, 44 total pressures (fifth among all defensive tackles) and he placed fourth overall at his position in Pro Football Focus's Run Stop Percentage metric. Michael Brockers, a first-round pick in 2012, has the other tackle position sewn up for now, but the depth on this line is pretty special, as well. Former Lions tackle Nick Fairley is now in the rotation, tackles William Hayes and Eugene Sims will get reps, and 2014 undrafted end Ethan Westbrooks has a lot of potential.

2. Miami Dolphins: This line was already pretty special before the Dolphins made Ndamukong Suh the highest-paid defensive player in NFL history. But now, that front four looks pretty impossible to stop at all levels. Suh is the point man, of course. He's the best 4–3 defensive tackle of his generation when he's on, and his ability to command a constant double-team opens things up for the rest of this group.

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Whichever side of the line Suh plays tackle on, there's also an end with great ability to rush the passer. Cameron Wake finished third in total pressures for 4–3 ends last season with 65 (per Pro Football Focus), and right defensive end Olivier Vernon is the sleeper of the unit who's ready to explode. Not only is Vernon great against the run, he's also got double-digit sack potential every season, which he exhibited in 2013 with 11.5 quarterback takedowns. The fourth-year man from Miami could benefit most from Suh's presence. Rounding out that front four is run-stopper Earl Mitchell, an underrated tackle who will keep things together at the point of attack while everyone else is running around after the quarterback. Miami didn't just take Suh from the Lions;they also signed veteran C.J. Mosley, who filled in credibly last season when Nick Fairley was hurt.

3. Buffalo Bills: When Rex Ryan agreed to become the Bills' new coach, he found himself with one of the few defensive lines more impressive than the one he left with the Jets. This is a monster unit capable of blowing out run games and terrorizing quarterbacks out of a base front with very little schematic diversity—the mind reels at how much havoc these guys will cause in Ryan's advanced pressure packages. Tackle Kyle Williams has been at this in Buffalo since 2006, and he's the rare interior defender who seems to only get better in his thirties. Williams has 16 sacks over the last two seasons, and he's the leader of this group. Marcel Dareus, who will play nose tackle in Ryan's base scheme, is the run-stopper who sets double teams aside and creates negative plays at a very impressive level.

In Ryan's defenses, the line between ends and linebackers is a pretty blurry one, but Mario Williams and Jerry Hughes essentially played end last season and will continue to do so in Ryan's frequent nickel and dime packages. Williams is the speed rusher off the edge from the left side, while Hughes, the former first-round bust in Indy, has 10 sacks in each of his two years in Buffalo. Add Ryan's playbook to this group, and third might be too low a ranking for the 2015 season.

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​4. Seattle Seahawks: The Seahawks were able to get past injuries to defensive tackles Brandon Mebane and Jordan Hill late in the season for one reason: Michael Bennett. Classified as an end, Bennett is actually one of the NFL's best hybrid pass rushers and run-stoppers, and Pete Carroll played him more inside down the stretch. Bennett responded by leading all 4–3 ends with 87 total pressures in 2014, including the postseason. The Patriots had no answer for him in the first half of Super Bowl XLIX until bookend Cliff Avril got hurt, allowing Bennett to be double-teamed more often. Avril is also a dynamic pass rusher, though age is catching up with him a bit, which is why Seattle selected Michigan end Frank Clark in the second round of the 2015 draft, a decision that earned the team a well-deserved public relations firestorm in light of Clark's history of domestic violence.

Mebane, the only starter on either side of the ball left from the pre-Pete Carroll era, is still a force at nose tackle when he's healthy, which is why he continues to dodge all those cap-casualty rumors. Seattle brought in veteran Ahtyba Rubin for depth. Hill came on like a comet in the second half of his sophomore season, with six sacks in the final six weeks. He's fully recovered from the calf injury that robbed him of the playoffs, and the Seahawks are expecting big things from him.

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​​5. New York Jets: The "Sons of Anarchy" drop a little as we all wait to find out if Sheldon Richardson will face more NFL discipline for his recent arrest—he has already been suspended for the first four games of the 2015 season for a violation of the NFL's substance abuse policies. Richardson's off-field trouble may change the Jets' long-term view of Muhammad Wilkerson. Amid his contract dispute with the team, Wilkerson is still a fantastic overall player. He is said to want around $12 million per year, and Richardson's situation gives him leverage. The wild card in Todd Bowles's defense is USC's Leonard Williams, taken sixth overall. Considered by some to be the best defensive player in the 2015 draft class, the 6'5", 302-pound Williams will spend his time as an end in base packages, but he may be the New York version of what Calais Campbell was to Bowles in Arizona: a pass rusher who can fire off from the three-tech and end positions in passing downs. Nose tackle Damon Harrison retains his role as one of the league's best run-stoppers.

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6. Baltimore Ravens: No Ngata? No problem. With edge-backers Terrell Suggs and Elvis Dumervil in the fold, the Ravens were going to have a stout pass rush whether veteran tackle Haloti Ngata was there or not. The Ravens traded him to Detroit in March with the knowledge that Brandon Williams is ready to become the face of that interior line. Williams doesn't move around the line like Ngata did, and he's not as athletic as Ngata was in his prime, but he's one of the best run-stoppers in the business. Baltimore will depend on second-year man Timmy Jernigan for more interior pressure. Jernigan racked up four sacks, eight hits and 12 hurries in 330 passing snaps in his rookie campaign; the Ravens think there's a lot more where that came from. Chris Canty was re-signed after considering retirement, but he's still got enough in the tank to make a difference.

7. Cincinnati Bengals: The 2014 Bengals finished dead last in the NFL with 20 sacks—yes, less than Justin Houston and J.J. Watt had as individuals. There were mitigating factors, though. Super-tackle Geno Atkins was still recovering from his 2013 knee injury, and his three sacks last season proved it. Early reports indicate that the real Atkins might be ready to roll again.

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“He’s real explosive,” defensive coordinator Paul Guenther said of Atkins in June. “He looks strong. He looks as good as he’s ever had. I’m proud of the way he’s come back. He gives us a huge boost. Huge. You’re talking about one of the elite players in the league.”

End Carlos Dunlap played well last season, but the Bengals never really replaced Michael Johnson, who left in the 2014 preseason for Tampa Bay's big money. That experiment lasted one season, Johnson was released, and now he's back in Cincinnati. That should help on both sides of the edge. Tackle Domata Peko might be feeling his age at this point, but he'll be part of a fairly talented rotation this season. As always, Atkins is the key.

8. Houston Texans: When your defensive line has the best player in the league, that certainly helps. J.J. Watt is the first player in NFL history to record two seasons with 20 sacks or more, and the stats don't really tell the story of how great he is. Watt rushes from different positions as the opposing offensive line's primary focus on nearly every play, and his supernatural combination of strength and speed makes him just about unblockable.

The Texans added Vince Wilfork, the former Patriot and possible future Hall of Famer, as their new nose tackle, and Wilfork has enough left to help on a situational basis. End Jared Crick is still putting it all together but has flashed some nice pass-rushing ability in fits and starts. The team needs more from nose tackle Louis Nix, who struggled with injuries in his rookie season. Based on his Notre Dame tape, Nix could be a top run-stopper over time.

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​9. Carolina Panthers: The Panthers played without Greg Hardy for all but one game in 2014 and picked up their pass rush with no issue. The key there was end Charles Johnson, who followed up his excellent '13 campaign with a season in which he totaled 72 pressures, which tied him with Michael Bennett for 4–3 ends in the regular season. With Hardy off to Dallas, it will be up to Frank Alexander, Kony Ealy and Wes Horton to compete for reps on Johnson's bookend. Where this line really excels is in its interior depth. Star Lotulelei broke his foot in the playoffs and re-injured it in early August, which could delay him through the preseason. Lotulelei has top-notch run-stopping and penetrative ability when healthy, though. The player to watch this season is tackle Kawann Short, the third-year man who has coaches buzzing with his potential. Colin Cole and Dwan Edwards round out an underrated rotational group.

10. Jacksonville Jaguars: Wait ... the Jaguars? Yep. The Jaguars. First-round pick Dante Fowler lost his entire rookie season to a torn ACL, but there's still a lot of talent here. Defensive tackle Sen'Derrick Marks might be the most underrated player at his position in the NFL. He was fairly dominant through the 2014 season and finished with 8.5 sacks. He'll probably miss the entire preseason with a knee injury but should be good to go when the regular season begins. Jacksonville signed former Dolphins tackle Jared Odrick to help Marks in the middle and perhaps become the primary interior pass rusher if Marks isn't available for the start of the season.

Fowler was supposed to be the primary pass rusher on the outside, but that responsibility will fall to veteran Chris Clemons once again. Clemons pulled off an eight-sack season in 2014, but he'll turn 34 in October. The guy to watch on this line is Ryan Davis, one of the league's best multi-gap pass rushers. Davis has developed into a Pernell McPhee/Michael Bennett-type weapon who can get pressure from just about anywhere on the field.

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