There are 3 that I like the most.
The complete control over time. Fast forward, reverse, stop. You'd be unstoppable.
Shapeshifting. I have a different view on this, though. Basically, imagine you'd be able to shape shift any part of you into whatever you wanted simply by thinking of wanting that part of you to be as such. You'd basically end up a kind of goo-y creature that can't really be killed, but can turn into anything at all desired.
Control over the elements (Air, Fire, Water, Earth... and Heart). Fly around, burn people, make a house or armor or weapons, and make a... killing... at the beach/swimming pool.
Of coarse, if you want to be cheap, you could just have that power to never die unless you wanted to, and to kill anyone you wanted to by looking at them and thinking happy thoughts...