I think Jackman's FC soundtrack was the best. I didn't dig the direction that Singer gave Ottman in terms of the kinda synthy nature of some songs. But just like how Thomas Newman (or whoever did it) revamped the On Her Majesty's Secret Service theme for the Spectre trailer, I bet if Ottman revamped the 90's TAS theme for our first big trailer of Apocalypse, we'd all collectively lose our minds. Everyone knows that song.
I'd also like to see Kamen's Rogue and Logan theme make a return. Unless Ottman creates some love theme for Scott and Jean in which case, that'd be cool. But I'd kinda like the Kamen one to remain as a motif somewhere.
Oh, and if we're gonna get anything Phoenix related, I hope we get a throwback to the Powell Phoenix theme. That one was a good one.