I voted for the original Shinobi, but that refers to the arcade version, not that damnable SMS version. I just feel that the original has the tightest control and best challenge level. I enjoy Revenge / Shinobi III (and in fact Shinobi III would probably be my second choice), but I do feel the health bar thing detracted from the game. It makes you feel like more of a ninja when you have to get past some of the trickier levels without taking a hit. I used to play Shinobi every single day in the arcades, and it definitely inpsired some heated high-score competitions!