My choice would be the all powerful Plot Armor. Armor that protects you from any danger because I am somehow important in the overarching plot... at least until the plot demands that I die... just kidding.
I am torn between my armor in Halo Reach (with all the armor abilities, like the AI team mates in campaign seem to have) and the Nanosuit 2.0 from Crysis 2. Both suits are virtually unstoppable and both can turn invisible (with the cloaking armor ability in Reach), but I like the Nanosuit 2.0 for how it's easy to hide, but I like armor in Reach for the Jetpack. Actually, thinking about the universes they come from, I think I would like to wear the armor from Reach because I would have allies as opposed to being hunted by everything with legs for the greater part of the game, er I guess life, in this case.