I get off to much messing with peoples mind. If I could choose one power, it would be themale version of Mystique from X-Men. Turn into Hermiones boyfriend and fuck her. Shit, fuck a lot of people you wouldnt normally be able to. Assassinate an insanely rich person (cause you could literally walk right up to them as their most trusted adviser), kill them, impersonate them, take all of their money. Repeat this process with maybe the President or someone else in power. Methodically take over the entire world.
Lets see.... Lust - Check, Greed - Check, Gluttony - Check, Sloth - Check, Wrath - Check, Envy and Pride - check, check. Yea, Mystique will do just fine.