HIGHLY debatable, IMO. Since 1992:
Steelers: 214 wins, 121 losses, 1 tie, 14 postseason appearances.
Patriots: 210 wins, 126 losses, 15 postseason appearances.
Yeah, the Patriots have won one more SB in that time, but they also lost one more SB in that time too. The Steelers last won a Super Bowl 4 years ago. The Patriots haven't won one in 8. And they won their 3 under HIGHLY dubious circumstances that Goodell conveniently swept under the rug. Not to mention the Steelers have shared the AFC North with a fierce rival in the Ravens, while the Jets, Bills and Dolphins have spent the last decade+ being the Patriots' punching bag for the most part.
But since ESPN sucks them off 24/7 and makes them out to be the greatest fucking thing since sliced bread, people seem to think the Patriots tower over everyone else in the league. 'Tain't so.