Now this one is a more difficult topic to answer.
Undertaker has a very strong case because in-ring he's probably their best active wrestler when he turns it up to 10, has insane amounts of credibility and notoriety, gets MONSTER reactions and I mean.... my parents know who the Undertaker is, and they've never watched wrestling.
However, he isn't at 10 very often because he doesn't appear very often, and his work on free TV is normally in cruise control. His sporadic appearances, frequency for injury etc make me wonder if we should look elsewhere.
Randy Orton has come along leaps and bounds, but I'm not sure if his pure wrestling ability is good enough for him to take this. His style is slower, more methodical, he doesn't do many moves etc and he really doesn't change up his game at all, so you could argue he isn't very versatile, but if it works, why not?
Edge is a very complete wrestler. His charisma and promo skills out of the ring are of the highest standard, and while I wouldn't say he's ever been in contention for the best in-ring wrestler, he's by no means far from the top. Big crowd reactions too.
CM Punk is underrated because he seemingly has a glass ceiling. He was very briefly allowed top-billing on cards, but then he ran his mouth and Undertaker returned to banish him down to the mid-card and later a great feud with Rey. He's an awesome promo guy, and love him or hate him, he's always stood out as unique in terms of his look and he commands attention from the crowd. He's very good in the ring, and actually quite an old-school worker. He's all about the little things. The fact he is predominantly an upper-mid-carder who occasionally main events may hold him back though.
I would like to vote for Jericho, but as a heel he intentionally handcuffs his own arsenal to make sure the crowd don't cheer. He literally has his two finishers and spends the rest of the match using submissions and strikes. It works for him, because the crowd eat up his matches, and he's the best talker in the company. He's very complete, but in 2010 he doesn't pure wrestle enough.
I guess Rey Mysterio's up there, but I personally don't care for him. A falling splash from the top rope from the top rope should not put people away. But he does have a marginally more exciting offense than most WWE guys and he does it every match. Kids go crazy for him and his act works against every single opponent. But he's never been a heel... does that mean he can't be considered the best overall? I think so. Not enough versatility.
Finally, Triple H. Say what you want about his position in the company, he is a good worker, and if you ignore his lazy spell in 2004, he always has been. He has good instincts, and the crowd normally eat out of his hand. He's been a great heel and a great face, he's dependable, and I don't remember him having any really bad matches against anyone but like... Scott Steiner. In terms of an overall/all-around game, he's a definite contender if you ask me.
So those are my nominees and I really don't know who to pick to be honest with you. There are knocks against each of them. Undertaker doesn't wrestle enough. Randy isn't a top notch pure worker. CM Punk hasn't properly been at the top of the company so it's tough to call him the best. Jericho intentionally doesn't put on great pure wrestling. Rey isn't versatile.
I'd say Triple H and Edge share common attributes. Neither is amazing in one area, but both are very solid in every area, making them extremely well-rounded, which is the whole point of an overall best wrestler. So... tossing up a coin between them... even though I find Edge a little bit more boring because he hasn't done anything new in a very long time... I think he wins purely because I don't want to have the arguments with people about how good Triple H is, because let's not forget, he married the bosses' daughter.
Winner: Edge via me forfeiting my case for Triple H.
