Hellion, Surge, Wind-Dancer, Rockslide, Icarus and Prodigy.
I picked Hellion and Surge because they've gotten zero play in this era, and were two of the 'main characters,' I felt, in the Academy X era (along with Prodigy, and, later, X-23, when she joined up).
Wind-Dancer is a favorite, and I'm not even sorry (and I wasn't going to have a six person team with five guys and one girl!). She *might* be involved in X-Corps, but, frankly, I don't trust that book to A) use her much at all (like Bishop in Marauders or Gambit in Excalibur, on the team in theory, but never doing anything significant in practice), or B) last all that long.
Rockslide and Icarus, while not even close to my favorites, have important / compelling story beats to explore. Rockslide is all sorts of messed up, and full of almost unlimited potential, at this moment. Somebody's gotta open that box and find out if this cat's alive or dead, and who knows how many things will pour out when they do? And Icarus, ooh boy, here's a dude who has been resurrected into a mutant paradise filled with people his actions got killed, because he *hated* being a mutant and mutilated himself and joined a mutant-killing death-church (that murdered him, and Wallflower, and tons of others)! There's one hell of a story there! Is he still all self-loathing? Do any of his former peers resent him for getting them killed? What's his relationship with his family, who include tons of mutants, who he hates?
I would be inclined to pick Elixir for a sixth, because he was good for drama, but he's gotten a ton of play, and, frankly, is utterly unrecognizable as a character from the punk he used to be. Same with Anole, he's a completely different character than he was, and I have zero interest in this new naif.
Dust is a favorite, but kind of dull. I'd love to include Indra, but, sorry dude, you're not as compelling to everyone-who-is-not-me as the rest!
For a sixth, it would have to be Prodigy, the last of the 'big names' (other than Laura) from that era, who I would have skipped because of his role in X-Factor, but if X-Factor is kaput, then he needs a place to land.