I'm usually one of those people saying "don't pay too much attention to rankings" but the difference in yours is not insignificant. I think Surrey and Sussex are quite similar reputation wise, but Kingston and West London are quite a bit lower.
If you really want to be in London, by all means go. But don't go because of your friends, you'll make new friends, and honestly if you're around your old friends all the time it might hold you back somewhat in making new ones. Part of uni is throwing yourself in and making the best of it.
Surrey vs sussex wise I would have to put my vote in for Sussex. Brighton is a really incredible city and Sussex has a wonderful campus.