I think We need to get something straight!
The Megadrive had Street Fighter II: Special Championship Edition - this was FASTER than Turbo which came out on the SNES.
The above fact Plus the 6 button controller on the Megadrive meant that playing SF on the megadrive was a much better experience closer to the 6-button arcade machines.
I will never understand why so many think the SNES had such a great controller anyway - ok it had 6 buttons fromthe get go but, and lets face it, the shoulder buttons were, frankly, TERRIBLE. it was like someone stuck them on as an after thought - they were so cheap and had zero travel.