Either Darth Vader or Captain Price. As Darth Vader, I'll destroy the rebel base, ***** slap my son into submission, finally kill the Emperor, declare myself supreme warlord of the galaxy, use the power of Soul Edge to resurrect my old padawan, then sit on my space throne and look bored, like Conan, like Conan. I'd also invent the force slap, a technique that would allow me to extend my pimp hand across space and slap anyone, at any time, anywhere, and in the face.
As Captain Price, I'd conquer Russia, use my new army to destroy the Middle East, kill that fucking general that killed Roach and Ghost, finally save the world, and go for a pint.