The Boots of Kicking Your Ass
An item I made in the Warcraft 3 item editor that makes you beyond uber. Invincible, massive attack boost, and some more stuff I forgot.
I also made The Bow of Burning Things, Gloves of Cutting You, The Shield of Stopping Things, and the Helm of Helming things in Oblivion (as well as a less uber version of the Boots of Kicking Your Ass). I'd rather have the WC3 Boots of Kicking Your Ass over those though.
Failing that, the lamp from Disney's Aladdin (it had video game versions). Who would not want Robin Williams around to grant you 3 wishes?
Failing that, I'd settle for either a Daishi or Vulture from Mechwarrior. Maybe a Puma if I can't have either of those.