I find you can't go wrong with Vango sleeping bags. I have a 3 season goose down one, It's fantastic. Incredibly small and light, and it keeps you warm. Only problem, be warned that if you are camping or outdoors do not let the goose down get wet!
Vango sleeping bags are not the cheapest, but with something like a sleeping bag, you are better off forking out for quality that lasts over cheep and cheerful!