Fable 2 was probably the best of the series in overall however in difficulty it really did lose out. I think I died once maybe twice during the course of the game. Fable was probably one of the most difficult games I remember playing on the Xbox, particularly the final battle with Jack of Blades. And honestly, Fable 3 sucked, in fact there aren't words to describe the sheer suckage that comprised Fable 3, it actually managed to retroactively ruin One and Two for me.
Pffff. Fable (with TLC) was the best one. It was a challenging game, with a good story, big world and nice characters. I felt that each game got smaller and less fable-ish.