[SmG Phoenix]

I just thought this would be an interesting debate. I'm talking about raw power here so physical strength, speed, magic, etc, otherwise if we brought Light or Lelouch in, this would be settled too quickly.
I'm temporarily going to nominate One Punch Man, until there is any mention of his limits. Only stats known are that he can travel near speed of light and punches with far more power than 100 tons which is all I can gather.
Goku is actually up there in terms of raw power.
In terms of magic, Negi Springfield is the only one that comes to mind atm.

I could start a Marvel/DC universe one, but pretty much One-Above-All becomes instant win, so RIP.