I'd like time manipulation. Not time
travel, because I'd worry about screwing up the past. Just the ability to speed up and slow down time on demand. I could sleep in every day in the hours between 7:18 and 7:20.
Either that or changing material states. Melt buildings, solidify water, elasticise pavements into trampolines etc.
If we're going for pure cool, teleportation is about as slick as it gets. It's something with so many practical applications I can imagine becoming blasé about using it.
If it has to be something mundane, the ability to fall asleep and wake up on demand. Seriously. Lunch break? Clap your hands and take a nap, wake up exactly forty minutes later and get back to what you were doing, refreshed.
A friend of mine said he'd like "antikinesis", the ability to rob moving objects of momentum. As well as Neo-esque bullet catch shennanigans, he likes the idea of halting a villain in space and watching them slam into the face of the Earth at 107,000 km/h.
No game-breaking omnipotence please. Summoning objects on command would be cool, but one
Ptah is enough.