Personally I get my franchise enjoyment from NFL 2K4, whilst leaving the updated 2K5 rosters for exhibition matches only (without worrying about the stats etc).
For me, apart from lowering the kickers accuracy and consistency ratings (coupled with my sliders), 2K4 plays a really good franchise mode. The only blotch is the low number of tackles CPU CB's get, although I don't think 2K5 fixed this issue either.