Melee > 64 > Brawl > Smash 4
Based purely on gameplay, Brawl and Smash 4 would switch place. They both share the same flaws though (weak combo potential while overly rewarding defensive playstyles, leaving little room for exciting gameplay). The reason I put Brawl ahead of Smash 4 anyway is because Brawl has better music, a real tournament mode and an actual adventure mode, making in more enjoyable on a casual level at least.
Additionally, if 64 had more characters and stages, I'd consider ranking it above Melee. As it stands though Melee has by far the greatest variety and potential in terms of exciting gameplay.







