I honestly could care less about Mega Man in this game, I didn't like using him in MvC2 because he just wasn't fun. Zero on the other hand I've thought was perfect for a fighting game ever since Mega Man X4. All of his moves were essentially something that you would see in a Street Fighter game.
Deadpool is awesome with a side order of fries(chips). Even though he's kind of getting played into the ground, he is an interesting character. He is insane and is fully aware of the fact that he is a comic book character, and he often breaks the fourth wall kinda like how he uses his health bar as a weapon in the game.
The only roster member I could really care less about is Haggar(I don't like Zangief either), but I won't use him anyway. The lack of Ken is a little upsetting, but I can deal with it.
As long as the roster is balanced I'm content.