Stone Cold Steve Austin.
Forget about the fact that this man basically ushered in the Attitude Era and was the John Lennon of wrestling in the late 1990's, take a look at his ring work. His grasp on in-ring psychology was surprisingly tuned and if not for Owen Hart botching that piledriver, he wouldn't have had to switch up wrestling styles in order to preserve his career. The Rock was pretty good in the ring too but I always appreciated how Austin was able to adapt and still keep the crowd on the edge of their seats.
Next, come his mic skills. Stone Cold Steve Austin's mic skills were absolutely incredible. After Bischoff gave him the boot from WCW, he used his real emotions and aggression to refine his mic skills in ECW before he jumped ship to the WWF and once he got time to be on his own after DiBiase left, he was on fire. Every word he said, he spoke with absolute confidence and was able to convey a man who got jerked around one too many times. His rivalries, before turning face at WM 14, with Bret Hart and Brian Pillman, were when he was at his absolute peak. It's easy for people to fake anger in order to get over and prove a point but Austin used real life experiences and crafted it into something that you would want to hear every time he held a microphone. And of course, later down the road, Austin was still witty and funny enough to get enjoyment out of and is one of the few wrestlers to retain his skill years AFTER retirement.
The Rock was also impressive on the mic. VERY impressive. He had a lot of one liners and catchphrases that captivated audience all around the world and face or heel, he always had the crowd in the palm of his hand. But the thing I really don't like about The Rock is the fact that most of the time, he was never really all the practical. Whenever the time came for him to get serious, the only thing he could really respond with was the fact that his opponent's haircut looked ridiculous or that he was a closet homosexual. He always seemed out of place when he had to oppose someone because his mic styles killed off any tension and made it look like a cartoon-esque farce. In fact, the only time where I remember him when I could take him seriously in a feud was before he became "The Rock" and vs. John Cena.
Therefore, because of his practicality, mic skills, in-ring work and look, Austin gets my vote.