Here’s how I’d describe them all:
Smash 64: The best of the best, the king of kings, the original one of legends past.
Melee: BS tier list placements galore, but still a fun game.
Brawl: It had an overrated theme song, but amazing gameplay and fresh new additions.
Smash 4: How I got into Smash. One of my favorite Smash games up there alongside 64.
Ultimate: (internal screaming while THE MOST TERRIBLE THEME SONG IN ALL OF SMASH BROS. plays) But aside from the annoying cringe that is Lifelight, Ultimate is just like Brawl in terms of gameplay and new additions.