That's not it at all, actually. I'm a big fan of Manning and unlike most Patriots fans I always have been. He's a class act and a genuinely likable guy. My main reasons for disliking the Colts are that a) they're our biggest rival, we play them pretty much every season recently and b) Bill Polian is a whiny douche who got the NFL to change rules in his favor (ironically, those rule changes benefited the 07 Pats as much as anyone).
I don't see the point in comparing him to Brady. Both are first-ballot hall of famers, I'm just glad I've been able to watch both of them in their primes.