I've been running SUPERS! campaigns for a few years now and I have to say I absolutely adore the system. It was designed with super heroes in mind, but it's so flexible it works with just about any setting you can imagine. I've actually never used it for super heroes, but I HAVE used it for medieval fantasy, space opera, horror, detective, mecha, and cyberpunk campaigns. As a GM, it's my favorite system to run by a mile and I've ran a LOT of systems. Give it a try!