The best system utilities and repair software, that will help your system run smoothly. CCleaner free edition easy to use and the free version, and can fix any window problems. It will use less ram of your system, occupy less space, that's why it's in the first place. Avg tuneup also the same as CCleaner but with some extra feature, it makes pc little laggy, takes a lot of rams, and more space in your pc. Rest depend on your taste, and also on your system specification.