As a former smash t.o. smash 4 is definitely the most fun to watch competitively as well, much better than fox v fox lol but both games have their upsides, hopefully smash5 blows them both out of the water
I've played them all, but am not a 'hardcore' Smash fan, and my favourite has definitely been Melee. I really enjoyed Subspace Emissary from Brawl though.