I think the "it" factor has to do with a lot of things. Obviously you have to be good on the mic, that is what made the Rock so great. I absolutely love the Rock. I didn't even watch wrestling when he was around and I live on youtube just watching his promos. The dude could talk like no one I've ever heard. For the Rock his "it" factor was the mic. But I don't think thats the only thing. I mean I think a lot of it has to do with the entrance that a superstar makes. I mean Kane hasn't done anything in the last year, but his entrance is just soo sweet imo(I saw it live from the 4th row and it blew me away, literally with heat lol) that I just get excited when he comes out.
I really don't feel that MVP has that "it" factor yet. Don't get me wrong he has a lot of talent and ability, both on the mic and in the ring, but I really don't think that people in the crowd really respond that well to him. I mean I don't really see him get a real great heel pop when he comes out and I don't really hear people really rooting for him.
Right now the guys that have "it" in my opinion are:
Mr. Kennedy(I love this guy, absolutely phenominal on the mic, talented in the ring, he has "it" according to me and I can't wait for him to get a big push, hopefully by winning the IC belt soon)
HHH
HBK
Undertaker
John Cena(I don't personally like him all that much, but I'm curious to see what happens when he returns. I was tired of him as champ, but when he comes back without the belt it might be pretty entertaining)
CM Punk(This one might be a bit of a reach at this point, but he really has a lot of talent and the crowd really gets behind him in his matches)