It's completely subjective, so there are no wrong answers. But in my opinion, it's definitely The Rock.
He transcended the wrestling game like no other, Hogan's a distant second in that regard and nobody else is close to Hogan. Rock is a genuine mainstream celebrity. Almost everybody knows who he is.
He was very good in the ring. Not necessarily the best worker, but definitely a very good worker with great selling ability and (in his prime) stamina.
Played both heel and face roles extremely well.
Cut promos better than anybody including Flair (yeah, Flair was great, but occasionally he sounded like he had a mouth full of marbles. Rock was always clear, articulate and damn funny; Flair at times didn't make a lot of sense). Rock had more memorable catchphrases than anybody.
Put over a LOT of guys to make them bigger stars and never put up an argument about doing that, so he put wrestling above himself many times, which is rare.
Represents wrestling in the mainstream better than anyone else. No scandals. He's not a drunk or a drug addict, he's not broke, he won't be wrestling into his 60s like some people do because they need the cash. He's the opposite of what Mickey Rourke's character in "The Wrestler" represents, and what a lot of non-fans perceive wrestlers to be.