My number one choice would be Darkstar. This is the easiest way for her to make a return, after having been killed off so ridiculously in NEW X-MEN by Grant Morrison. So far, Mockingbird has returned (or so it looks right now anyway) and this makes me happy, so I'll take her until a writer brings back Darkstar.
I know I'm not the only Laynia fan, too.
Heck, who needs the Skrulls. The Presence brought back Vanguard, so maybe he could pull a whammy with Darkstar. That would be so fetch!