In terms of total package (wrestling ability, mic skills, etc. all wrapped in one), I'd say Owens is the best, but AJ is a very close second, for me. When it comes to pure wrestling ability alone, I'd say Cesaro's the best in WWE right now, with Sami, Neville and AJ close there. Pure promo ability, Bray Wyatt, with Owens, Miz and, maybe, Dean close behind him. For both total package, Owens and AJ are about neck and neck, in my opinion, but Owens very slightly edges it for me because I think his promo ability compared to AJ's promo ability is better than AJ's wrestling ability compared to Owens' wrestling ability.
The fact that those two are the two top champs in WWE right now makes me happy, tho. AJ, from the sound of the reaction he gets anytime his music hits or he appears, does seem to be the most over wrestler in WWE at the moment (maybe even in the world). I'm glad his mic skills have improved to the point they have. I haven't seen much of AJ pre-WWE in terms of promos, but I remember the bits I've seen being pretty bad. He's very good in his current gimmick, though.
Plus, he's one of very few "new guys" who actually beat Cena clean, not just for a single match, but for the feud in general. That doesn't necessarily mean anything in terms of him being a better wrestler because of it, but it did help get him even more over than he was before and shows that the staff got faith in him.