IMO Manning has had the better supporting cast over the years: Harrison and Wayne are HoF's, Clark, James(RB), Pollard are his top 5 targets of all time. Compare that to Moss, Welker, T. Brown, K. Faulk(RB), Branch. It's close for sure, but look at the list that has played for Manning both currently and in the past and he gets the edge.
And Belichick is a great coach. I wasn't around for Lombardi, Walsh, or Brown but much like hockey I think these old coaches are overhyped. When he calls it a career he should be top 5 easy.
And Patriots wont do anything in the playoffs if they don't pick up a veteran receiver, period.