With Ryce (leak) confirming that X-men & Fantastic4 characters will only available through DLC - Its pretty much guaranteed that Wolverine, Magneto, Storm & Doom will be included for the Marvel side (I'm not happy about that but whatyagonnado).
That'll leave 1 or 2 Marvel Characters left (presuming that the dlc pack will be 10-12 characters - Half Marvel/half Capcom).
Who out of the remaining X-men/FF characters would you like to see fill the last one or two spots? For me...
1st - PSYLOCKE
2nd - GAMBIT