Horsham is gorgeous - I worked there for a bit in the 6th form college. Nice teenagers, polite people, gorgeous town centre. DH and I are moving to one of the villages local to there as soon as we sell our house. Some areas are worse than others, but there are no really bad areas.

Not too far from London either so if you're in Horsham there are two train stations that can get you to central London in under 40 minutes, even for the slow trains.