I vote Taker, and he SHOULD win.
Lets get this straight first, what the undertaker has accomplished
Hogan era - defeated Hulk Hogan in his PRIME for the WWE championship
-Jake the snake Roberts
-Jimmy snuka
-Ultimate warrior
-King Kong Bundy
-Yokozuna
-Bret heart
-Macho man
Etc
Attitude era - The undertaker was the most consistent in this era as well as being one of the best and beating the very best.
-Stone cold
-The rock
-Mick Foley
-Kane
-HBK
-Triple H
-Big show
-Psycho Sid
-Diesel
Etc
New age era - He cam from the past and defeated the future!!!!!
- John Cena
- Randy Orton
- Batista
- Kennedy
- Jeff hardy
- Booker T
- EDGE
(He defeated Ric flair at this time lol)
And above all this he is 16 - 0 at Wrestlemania
He came into the ME and has stayed there ever since
Hes not like Hogan and flair, in the sense that he just gets better and better not fatter and fatter.
Okay now Lets talk about skill, wrestling ect.
9/10 gimmick matches favor him.
The undertaker is a step above the whole typical WWE champion standard (Hogan, The Rock, Austin, HHH, Orton, Cena etc) The reason this is, he is taller and much MUCH more stronger (kayfabe, deadman persona) and in some cases has far more explosive speed.
Then theres the monster types who are unbeatable, simple as that however The undertaker is the anti-Monster, just look at his whole career and see just why. In every sense of the word better but in some cases not as strong (kayfabe strength eg Khali, Henry giant gozales etc etc etc etc etc etc...........) (btw including VADER!! Although he has my respect for a very good SHW)
After these main two types of wrestlers the Undertaker has come across, it still does not mean Taker cannot excel at Other things
Submission type wrestlers...
He has show he can brawl with the best ANGLE, BRET HEART, CHRIS BEOIT etc. Angle said it himself hes just simply 'the best'.
And now remember Taker still has that huge power force which is what makes him superior to these well talented wrestlers.
I would include the whole Steroid Moran clan but they make me sick!!!!!! E.g.
Batista (has beaten him)
Goldberg (not faced)
Brock lesnar (did infact lose to him, although he shouldnt have) (on a side note ill admit he had talent but if it means he wont take the business seriously I would rather employ Khali)
Bobby Lashly (not faced)
And everything, anyone else, I hate to say but they would get pummeled by The undertaker as Jeff Hardy did in their ladder match.
Finally I would also like to bring in HBK, as many people think hes the guy 'who can beat taker'. I have to say if someone comes close its HBK but so does Angle, so does BRET, so does Hogan in his PRIME.
Anyway The undertaker would Crush HBK in a gimmick match thats simply not disputable except maybe ladder or something which requires speed.
However in a normal match its very different, but once again
Endurance Taker > HBK
Power Taker > HBK
etc
The only thing which HBK has over Taker is speed, and frankly it isnt a HUGE difference and the fact that HBK is simple a Elite all round performer but once again so is Taker.