Which space army would conquer all the others?

Games Workshop has been trying to own the term "Space Marine" — but would their Space Marines be able to pwn the Spartans from Halo? And Heinlein's Starship Troopers? What about the Colonial Marines from Aliens, or Doctor Who's deadly clergy? Which space army would defeat all the rest?

Share your chosen victor below — and please don't forget to include a cool picture of the armor and shiny weapons!