I'd want to have the Sylar/Peter Petrelli superpower so I could absorb all the other powers in existence.
Time-stopping would be my first choice. There are some things that would have to come along with it: - things must not be hard as steel as suggested in the novel "The Girl, the Gold Watch & Everything", I want to have an influence on things - I must not grow older as in that particular Simpsons horror episode with Bart & Milhouse It would be great to do everything I ever wanted. I could learn 5000 Chinese Kanji without "losing" one day of my life, I could travel the world, learn to fly a Boeing or dive to the Titanic without anyone knowing, without any consequences and without growing older. I would probably spend years of my not-continuing life to search the Pentagon for hints on extraterrestrial life. I could also track down all the hardcore collectors in the world, break in, put their stuff on a truck and compile it to one giant collection.
But if you could stop time you could sneak into their bathroom while they are in the shower and touch their boobs. Isn't that like infinitelty better than just watching?
Omnipotence is a bad idea as every times someone has a shit or a shag they are putting their mess on, in or around you. Omniscience would be useless without understanding all of the raw information. Superintelligence will be useless without the information to fuel said intelligence. Being immortal in the undead mortal sense would be unreasonably restrictive. You would probably never evolve whilst everyone else around you changed or adapted to become stronger in one way or another. They don't have to kill you to defeat you. Imagine an eternity of torture. Fuck that! I think phase shifting could be one of the more useful. You could sneak into places as per the invisible man and still get your end away, game or whatever floats your boat in 'normal' phase then phase 'out' to avoid injury, thus it wouldn't matter if everyone knew who you was or where you were because they could do nothing about it!
That sounds somewhat like the Teen-rated censored version of what the regular guy would do with a girl in a shower with the time being stopped
I'm not sure what power I would want. But whatever, I'd be a 007 style super villain with an awesome secret base on an island somewhere.