Weapons' movement that leave a smooth, transparent trail. ie. SoulCalibur games.
Special dialogues between rival characters.
Characters' heads/eyes follow the enemy's so they are always looking at each other - aka Tekken, SFIV.
Good hair/clothes physics (can't wait for Uncharted 4 Nate's hair).
Hair/facial hair/body hair/body type options in character creations.
Skirt physics for female characters.
"Bikini armor", despite all hate it gets, I absolutely love it. Both my male and female characters fight as naked a possible.