I'm a Colts fan.
This year Brady looks more impressive than Manning. It helps that 2 of their 3 WRs are better than the Colts' (Moss>Harrison, Welker>Gonzales). However, I think Manning is playing smarter than he ever has, in that he's not forcing the gunslinging like he used to (and like he used to have to). He's learned to hand off when the D is playing the pass, he's learned to take what the D gives him, and how to play very effective ball control. He helps his defense, which is very undersized and fast and good at playing panicked offenses trying to catch up.
There are a number of ways you can look at this. How would Manning have done given the defensive safety net Brady has had his whole career? How would Brady have done had he been able to throw to Harrison his whole career? How would they do today if their situations were reversed? Would a control freak like Manning be able to take BB's micromanaging? Would Brady be able to mentally handle the complex Tom Moore offense?
Trying to definitely say one is better than the other is just kind of stupid. There are so many factors that go into a football win, and especially a winning season. Brady looks better now, but Manning has looked better in the past. But Brady has had fewer offensive weapons. But Manning hasn't had a defense to rely on. See? Round and round we go.
They're 1a and 1b.