My answer is unusual, somewhat complex but ultimately perfect I think.
I choose Arhur Petrelli's power from Heroes, which is the powe to absord and control anyone else's power. Then I choose Desmond's from Lost with the whole unstuck in time thing allowing him to break fatalism/determinism and rewrite the past and whatnot. Finally I choose the power of the Secret Original from The Filth, his powers allow him to enter and exit comic books.
You see how this works out? I can now safely enter any comic and steal all the powers of everyone in it. I'd specifically use it to steal the powers from Dr Manhattan, Superman, Goku, Morpheus, Martian Manhunter, The Flash, all the characters in The Authority, all the characters in Supergod and Darkseid. And they're just to start off with.