Hey,
I'm at Kingston at the moment on foundation, and have chosen to stay on for graphic design next year.
I can't comment too much about the course itself, but I have to say that the atmosphere is brilliant - down to earth and almost viciously friendly, and the one of my tutors who tutors BA as well is beyond fantastic. Chatting to people who are on degree at the moment, they're loving it too. When I first started foundation, most people were convinced that they were going to go elsewhere for degree, for the same reasons as you. In the end, 22 out of the 30 of us have been convinced (/brainwashed haha) into staying on.
Having said that, the other two courses you mention are also brilliant, and although Kingston is different from London in atmosphere, it is still pretty close by. Whatever you decide, congratulations! Maybe see you next year.