Honestly, I'd prefer it to be Daisy, I'm getting really tired of her. It won't be, though. I'd say May is most likely since I doubt they'll kill Coulson (that's already been done) and they've made a big enough deal of it that it won't be a lesser character. Lincoln's newish and they're trying to create drama with him, so the only other options are Mack, Fitz, or Simmons, aka the best three characters. I would be particularly upset if it was one of them. Anyways, I guess we'll find out very soon.