From most played to least played:
1. Vampire series (Unlike SF II, I actually like the majority of the cast, with the possible exception of Huitzil.)
2. Rival Schools series (One of the few 3-D fighters I do come back for more of.)
3. Street Fighter III series (Tons of new characters, most of which I actually like.)
4. Capcom vs SNK series (Regaurdless of how much people complain about these games, I prefer them over the Marvel vs games by far.)
5. Super Street Fighter II
6. Super Street Fighter II Turbo (10 times better than Turbo Hyper Fighting.)
7. Street Fighter Zero series (Same as SF III. If you can't tell, I have a major dislike for the majority of the SF II cast, which is why this series is ranked so low.)
8. Pocket Fighter (Another fun fighter. Capcom should make more of these.)
9. Cyberbots
10. Soul Edge (I prefer this over Calibur.)