Plot. I only ever played MvC2, so as far as I know, there's never really been one. And while I don't really care about plot in fighting games of this sort, a few "talking-head" cutscenes for each character and neat endings would definitely be appreciated.
X-Men vs. Street Fighter Endings:
http://uk.youtube.com/watch?v=drrGii8FbUs
Marvel Super Heroes vs. Street Fighter Endings:
http://www.youtube.com/watch?v=_iceIe7poLo
Marvel vs. Capcom 1 Endings:
http://www.youtube.com/watch?v=j6xQWYKVGxc
Also, when you kill someone with a Super Move, they need to bring back the announcer saying the name with Text on the screen. They should have it word by word like the Smash Bros. announcer so when you kill with a team-up move and it combines the names (like Shinku Hadoken and Mega Optic Blast becomes "Shinku Optic Blast") for the announcer to say instead of just screaming "SUPER COMBINATION FINISH!!!"
And I'm all for the Fantastic 4...but Marvel Knights? I don't know...the only one that really stood out to me (and that, y'know--I actually
read) was Doctor Strange...
I'd literally have a nerdgasm if Mr. Fantastic, Invisible Woman, Human Torch, and The Thing all made it in, even if only one is playable and the rest are cameos. I would literally explode with joy if Silver Surfer, the only one character in the Marvel Universe that I would dare call cooler than all of the Fantastic Four combined, was playable.
Here are some "Marvel Knights"
Doctor Strange
Black Panther
Daredevil
Black Widow (Natalia or Yelena, preferably Natalia)
Punisher (Capcom already made a Punisher arcade with Nick Fury as the second player)
Nick Fury (already playable in Punisher arcade game)
Ghost Rider
Elektra
War Machine (already made playable in MvC's 1 and 2)
Sentry
Luke Cage
Cloak & Dagger
Moon Knight
Shang-Chi
Marvel Boy (don't really like him but he has a fanbase)
Iron Fist
Along with many more. Let's nor forget the neglected members of the Avengers and the tons of unused X-Men (why no Nightcrawler?).There are
A LOT of characters to choose from.
If Hank Pym makes it in, no matter if he's Ant-Man, Giant-Man, or just Hank Pym, he WILL pwn.