I can't seem to find a poll option, but that just leaves more answers available. Obviously, some of these have already been released as PSP-specific titles.
King of Fighters
Persona 4 Arena
Tekken Tag Tournament
Dragon Ball Z: Budokai (or Tenkaichi, they're very different styles from Battle of Z imo)
Some, of course, have already been released, like BlazBlue, DoA, Injustice, Mortal Kombat, and SFxTekken. I acknowledge that I may have missed a few big ones, so apologies.
Personally, I'd love to see TTT, P4A, and the original Budokai (2.5D) series.
Edit: Changed labels. For more information on labels, please see this post: http://community.us.playstation.com/t5/PlayStation
Well, I'm a Dragon Ball nut, and I've been having a lot of fun with Battle of Z on my Vita. But I'd love an HD version of Tenkaichi 3 (cross buy/play with PS3 while I'm dreaming).
Beyond that, I've already got Injustice, MvC3 and MK on my Vita (all of which are really, really awesome). I've got the PSP version of Tekken there too, so that's covered. Honestly, I've been playing more fighters on my Vita than anything else.
Personally, I'd love a version of USF4 for Vita. KOF XIII would look gorgeous on the Vita too... although it's maybe too old for asking. A version of Tekken would be great too, as long as it isn't Tekken Revolution (it kinda sucks).
MK and Injustice are OK, but don't look very good compared to their console counterparts.And yeah, regrettably that's a turnoff for some, like me.
I'm kinda worried though, there's not many fighting games on the horizon.