Warbird kinda sucks. She had better find a way to reconnect with that white hole
I believe she's still connected, I think Busiek said that at some point she transported some dark matter or something into it, to save the world no doubt, and this sent the hole/star into the next phase of its existance, or collapsed part of its volume, limiting her powers.
She is an amazing power sponge, the more she takes, the stronger she gets, I'm assuming she would top out at a level akin to her old Binary abilities--but we've never seen her top out. I realize Johnny has a great deal of experience, but he has trouble absorbing stuff, and Carol has formal army and fighting training. I'm leaning towards her.