My vote is Street Fighter 2 Turbo

The Alpha games were better on PSX than SNES.
Street Fighter 2 Turbo played better, but Super Street Fighter 2 had more content. While my pick is Turbo, I'd say (between Super and Turbo) you can't go wrong.

I was quite blown away that the SNES could handle a game as impressive as SF Alpha 2 when it was also released for PS1/Saturn. 

The only major slowdown for the SNES version was that every time the round start it would pause for like 5 seconds. Someone did some digging and found out it was all due to the audio processor and could've been an easy fix if it was like now days and the easy game updates. Was definitely odd at first but got use to it. 

Super Street Fighter II, for me. Turbo is speedier and arguably more balanced, but I’ll take the extra modes and characters.

I’m also a fan of Ultimate Mortal Kombat 3.

I'll vote World Heroes - it was one of the big purchase mistakes of my gaming career that really hurt (pocket money was sparse back then), but this way I got some tiny thing out of it in the end.