First would definately be the USMC Marines from Aliens. Thier whole attitude summed up in one quote, "Just tell me one thing... Where they are."
Next, would be the forces of the Galactic Empire. Other than the fact that they are the most inaccurate troops ever seen, they get tons of points for style... Huge Star Destroyers, swarms of TIEs, millions of troopers and of course the giant walkers.
If I could have a working real-life vehicle from any movie, it'd be a hard choice but I'd pick the Star Destroyer. It includes all the walkers, troops and ties you'd need for some fun.
YodaMan