It varies person to person honestly.
To me a fighting game needs to have a sort of balance that the player can know to exploit abilities using quick thinking strategy. I really hate cheap difficulty in fighting games that devolve into spamming a move. There also should be tiers that beginners can enjoy simple moves, but can tell more experienced players that learn habits, patterns and develop strategies.
Independently of genre is style and aesthetics. Fighting games to me need memorable characters that add personality. As fine tuned a game may be, if it was just wire frames fighting I think I'd get bored still.