For me this comes down to wanting a character who is either powerful, or has the potential to use their abilities in a number of imaginative ways. My second consideration is to read about someone who doesn't have years of detailed, in-depth history already. Enigmas are just more fun to read imho. And I tend towards characters who have untapped potential. So my vote goes to Tempo.
But if Tempo does win, for the love of God, please, please, please refresh her look. I don't mind the metallic gold armor/uniform per se, but the bucket helmet always bothered me. I'd like to see her face and hair. As for the electronic features in the helmet that prevent psionic intrusion, maybe update the science from the stone age to something more modern, like cerebral nanotech implants that offer the same protection? Or just build it into her power by establishing that her mind is neither here, nor there due to constant shifting from past to present to future and across near infinite timeline divergences, even when she's not actually using her powers, which makes her thoughts particularly slippery to grasp, even by the most powerful telepath. Or something like that.
After Tempo, Polaris, Banshee, Sunspot and Forge are my picks in that order.