SFC vs USA cart

-Loses 25 seconds in US due to slower rolling text

-Some sprites are changed

-SFC carts allow you to shoot Wham Bam Rock with plasma when he is offscreen, US carts do not. This is insignificant if you don't mess the fight up.

-US carts take an additional 1 second (59 frames) per reset to start the game again

SFC 1.0 vs 1.1

-How your momentum is conserved when you release a puff when in water is different. Only matters in the final room of Halfmoon.

Emulator

-The newest versions of snes9x should be the best, I suggest playing through Retroarch to minimize input delay

Virtual Console, Dream Collection, SNES Classic and Switch Online

-Reduces lag compared to SNES

-Removes animation where the screen flashes after killing any boss, saving time

-VC and Kirby Dream Collection runs at a lower framerate, losing time but still saving a little overall due to the boss animations

As long as you don't have record no one cares if you use VC or SNES Classic, just be wary of the inherent advantage. I encourage re-release versions to be run for epilepsy precautions.