Gender: Male Location: Following the Source of Light.
Empire (in military terms): The Borg. The Dominion have more troops, but I doubt it. Regardless, the Borg have much more powerful ships and effective techniques.
Single Weapon: A lot to choose from here. The trilithium probe from ST:Generations was pretty destructive. The Transphasic Torpedoes from the Voyager finale were also pretty impressive. Dunno if this counts, but the Krenim's temporal weapon would be tops for me, since it can pretty much erase entire civilizations from the space-time continuum.
Starfleet Ship: In the 24th century, either the Enterprise E or the USS Prometheus. Since the Prometheus is technically only a prototype, I'm inclined to go with the Enterprise.
Non-Starfleet Ship: Again, I'm inclined to go with the Krenim Weapon Ship. Not even the planet-busting Doomsday machine or 8472 can come close to the destructive effects of the Krenim's temporal weapon.
How about those modified photon torpedoes "Charles Emmereson Winchester III" lobbed into some alien sun in the Next Generation series? IIRC, it took only six of them to push the star into nova/supernova mode.
Shinier than a speeding bullet.