Levitate
Water Absorb
Regenerator
Bulletproof
All of these abilities would be good, in my opinion, but I think Bulletproof is just a bit too specialized and may become less relevant as the metagame develops. To be honest, I'm a bit split on Water Absorb and Regenerator for second place--both would be great on CAP26, but I think Levitate would be just a bit better.