SF4, so far. I like the idea of an Ikeno/Akiman-esque painting come to life. I’m not sure it’s there yet but hopefully this will become more apparant over time.
The other thing I like about SF4 is that FINALLY when the characters turn around they won’t be just mirror images of each other, so Sagat’s scar and eyepatch will be on the correct sides, always. The only 2D Capcom character that debunked this was Gill of SF3 but it was really a color and effect swap with his fireball. Balrog (claw) will still have the mirror image thing going for him or his claw will switch hands because it would throw things off in this game but I can live with that. Balrog just wouldn’t be the same if he had two claws or anything like that, his appearance in Iron/Cannon Spike aside. 
Currently as in what’s out right now, I’d say Third Strike. That level of 2D animation still holds up today even with the likes of Guilty Gear.
Way too early for me to form an opinion on either the HD game or Tatsunoko vs. Capcom. Or at the very least, I’ve seen more of SF4 than these other two games honestly.
On SNK’s end, KOF XII is shaping up very nicely. Good year for fighters. :tup: