All of them lmao. There's absolutely no point to go back to any of them after Ultimate.
I actually really loved the 3DS version of Smash 4 because of its portability, plus it actually felt really nice to play on the system.
Predictions for global hardware sales by end of 2017: PS4 - 70M. Xbone - 33M. Switch - 7M.
"There is a need for parents to touch children first." - Tatsumi Kimishima, 2017