From the LA Times, via PFT [emphasis mine]:
Strictly as a player, however, Roethlisberger hasn't gotten the respect he deserves. There are many theories for that. He's a lumbering (but effective) runner. He frequently holds on to the ball too long. He plays for a franchise traditionally known for its defense and power-running game.
"Bottom line, if you ask football people, they're going to put Ben Roethlisberger up there with [Manning and Brady] almost unanimously," said Bill Polian, Colts president. "No one would leave him out. And others who have made the Pro Bowl, for example, wouldn't even get consideration if you took a poll of all 32 general managers."
It's worth noting that Ben Roethlisberger has never won a league MVP while Manning and Brady have (soon-to-be) six MVPs between them. It's also worth noting that when the Steelers have had a defense unable to get teams off the field (as they did in 2006 and 2009), Roethlisberger has been unable to guide the Steelers to the post-season.
Brady guided the Patriots to the post-season this year with a sub-par defense, and Peyton Manning's entire career is forged around compensating for poor defensive play in Indianapolis.
I agree that Roethlisberger should be considered 'better' than other QBs many have put ahead of him, like Drew Brees and Michael Vick. But, to say he's 'up there' with Brady and Manning is a stretch.
But, if Bill Polian says it, it has weight. Then again, Bill Polian also thought Donald Brown, Tony Ugoh, and Jerry Hughes were each worthy of a first round selection. Just tossing that out there.