I would say the challenge and a shined lucid...
I would agree with the Challenge, though I may also say the Champion, from what I've seen of it.
Both the Challenge and Champion took technology in from what Ebonite was successful with before, with the One, Total and Complete NV, Mission, etc., in both core and coverstock. That's what makes the Challenge a killer yet underrated ball.
Personally, as I have both, I would think that the Challenge is a hell of a lot stronger than the original Mission. The original Mission was nice, angular, and smooth, while the Challenge turns and goes and keeps on going. The Champion is more of a pearl version of the Champion, but again, I haven't seen it thrown yet, and Ebonite's video of it leaves a lot to be desired.
I'd say either a polished up Challenge, or Champion in addition to that shined up Lucid.
BL.