I'd pick the one with the highest stats overall, focusing on AGI and WIS. If they ever do the Add-skills-to-leader thing that BB is doing, that leader will be the new best.
On that note, I'm not sure which leader has the highest stats now. The WIKI isn't updated with the new 130 stats, and the google docs spreadsheet still has lvl 99 stats even though the max lvl field is now 130.