We haven't discussed gaming systems in our "favorites" threads, so how about it? What gaming system (for role playing games) do you like the best? What is it about that system that makes you love it?
My favorites change, but right now I think that QAGS would be my favorite. It's a nice simple system that uses one game mechanic for resolving any conflict, whether it's combat or political debate or counting social coup. It allows some freeform descriptions in character creation, but provides enough structure that you don't get paralyzed trying to figure out what to do.