Gonna need feats from Ken and Sanosuke before I go. The other guy can go first.
@taichokage: Well in all honesty the only method I could think Enel could legitimately kill Whitebeard is with Raigo(If he had prep) other than that WB could one shot.
Theoretically, Enel should be able to zip out of the way and spam El Thor which could probably incapacitate him at the very least. I do agree at least power-wise(plus mastery over mantra) I can see Enel being potentially upper admiral level.