#1 Daniel Bryan

Both Daniel Bryan and Rey Mysterio have expressed a great deal of interest in working with one another recently, which would probably be a fantastic idea, especially when you consider the fact that it'd get Bryan out of feuds with mid-level opponents, and into a feud with one of the most spectacular in-ring performers of all-time.
Prior to returning to active competition, Daniel Bryan talked about potentially going to Mexico to do a series of mask vs. hair matches, which is something that he could do pretty effectively with someone like Mysterio.
Breaking Vince Russo and Jim Cornette update HERE.
Of course, it's probably pretty safe to assume that Mysterio will win the mask vs. hair match against Bryan if it were booked, simply because removing Rey's mask wouldn't be the best idea in the world, but even though the ending would be spoiled by the stipulation, it'd still be pretty great to watch.