I went with Marino, Elway, Brady, Manning.
I feel like the each occupy a particular archetype, and were the best of that archetype. So, for example Montana -- he's slightly under Brady, similar mold.
Or the drop back and find something, gunslinger -- that's Marino. Favre was a poor man's Marino.
Elway is the athletic, mobile, will his team to victory type (big arm).
I think Manning is on it -- the ultimate cerebral, read the defense before snap, change the play, etc. There has never been anyone better at that aspect.