Another Clay fan, here. I think Ruben is okay, but just don't see why he's so popular. Maybe I missed something in the earlier episodes (just came on a couple of weeks ago), but he just doesn't do anything for me. Clay, on the other hand, has the voice, and that's what counts. He can learn to do more on stage, but no matter what he's sung, he's nailed it in the ones I've seen.
Actually, I don't really *like* any of the singers on AI except Clay. Ruben is okay, Trenyce is good on certain songs and certain parts but some of the stuff she tries gets really off, Josh should be on Nashville Star instead (and conversely, Brandy from Nashville Star should be on AI instead), and the other three ladies just haven't done their songs that well IMHO.
The only exception I've heard was the God Bless America version they did as a group -- that was fantastic.