Gazillion has implemented a voting system that will allow the community to pick the next Marvel Heroes 2016 character. There's only a few options at the moment, but most of them are good. Voting is open now on Game Informer's homepage, and will run until September 30.
Your options include Angela, Gamora, Green Goblin, Ms. Marvel (Kamala Khan), Spider-Man (Miles Morales), and Wasp. Currently Angela, Green Goblin, and Wasp are notable frontrunners, with Ms. Marvel, Gamora, and Spider-Man far behind. I personally gave my vote for Green Goblin -- I'm surprised he wasn't in the game already.