I actually thought about this question far too much one day a couple of years ago, and got pretty bored with the general generic things people usually want. For me, I would be perfectly happy with these two powers:

1.) Being able to stomp powerfully enough to shake the ground violently and have the sound travel a great distance.

2.) Being able to perfectly mimic Godzilla's roar, as loud as you would expect from a giant nuclear mutant dinosaur.

I would pretty much spend my days travelling to various costal cities around the world waiting until night time to really mess with peoples heads. It would be awesome.