Fatal Fury 1.
Horrible game.
DING! Could never get into it, no matter how much I tried to respect SNK for making it.
Of my collection, the one I never really pull out would be Art of Fighting 3. I really just got it so I can play as Carmen, and play like a drug lord; picking people off the ground and punching them in the face, or beef punching the female characters. Out of about 40 carts I own, I have not touched that cart since maybe...February or March. Also in my collection, I don't really touch Samurai Shodown 1. It's not a bad game, I'm just too used to what you can do in 2, that I get pretty screwed when I go back to 1. 0h, and Real Bout 2, just got it because I have 1 and Special, I don't like how 2 really plays, but I do like how quick it throws you into the next match, keeps up the tension.
Also never got into the few sports games I've had on hand, but enough of my drunk rambling.