Of the 16-bit versions I have always thought the Mega Drive version was the best, it controls much better than the other versions thanks to the superior joypad and is also the fastest version too.PC Engine port is also pretty impressive too given the hardware.I have to admit though I have never seen what all the fuss is about regarding this game.
Shame they didn't cover the DOS version of Super Street Fighter 2 Turbo. It's probably the best version you can get on for a computer. It also minorly edges out over the 3DO version, since you're not limited to five buttons.Compared to pretty much every other computer version of this game out there, it's pretty much arcade perfect. I mean, look at the Amiga version.
A little off topic, but I've got a SF2:CE arcade PCB with the Rainbow Edition hack. The Rainbow hack is available in MAME also.It's hilarious to play against unsuspecting opponents. Looks and sounds like the original game but: you can fire multiple fireballs/sonic booms/etc in a row, some characters have fireballs added to their non-projectile special attacks, you can change characters at any time by pressing the start button, repeating some special moves let you 'fly' higher and higher until you're off the top of the screen, etc. It's chaos. There's also the excellent Super Street Fighter Turbo HD Remix update for PS360, with new graphics and online play.