Since I'm interpreting this as pure, in-ring wrestling ability, I'm torn between Jericho, Punk, and the newly acquired Bryan Danielson.
It's tough, but I'm going with Jericho. He's one of the best, if not the best, all around wrestler. He can mat wrestle, do technical stuff, luchador stuff, he can fly, he can submission wrestle, and can tell a story all in one. The guy can seriously do anything. Punk is pretty much the same and though I don't watch ROH, I have seen some of Bryan Danielson's matches and his ring work is phenomenal.
I'm sorry, but I could not let this slide. I'll admit that I'm not a Cena fan, but that has more to do with his character than his in-ring ability, which is quite good to be honest. However, one thing Cena has ALWAYS failed at is selling wear-and-tear.
John Cena has a long history of not selling long term damage. An example that come to mind are his match with HBK at WM 23 where Michaels worked on his leg for 10-15 minutes and Cena didn't sell it AT ALL. (the best he could muster was a leg shake before the 5 knuckle shuffle). Let's not mention him no-selling the punt at HIAC.
But the worst example by far was the Raw before the Hell in a Cell ppv. When Cena had to face Jerishow and Orton in the gauntlet, he got destroyed by Jerishow. He was in Big Show's colossal clutch for ages and in the Wall of Jericho even longer, and this was after they'd beaten the tar out of him. Then out comes Orton, Cena signals the cell to come down, and all of a sudden he's instantly rejuvanted, running around, beating up Orton, climbing the cell and even giving Orton the AA on top of the cell. A beaten and battered Cena destroys a FRESH Orton? What?
Sorry dude, Cena's good in the ring, but the only thing he can sell is merchandise.