I go to King's and I think the Law dept is amazing. Obviously I'm biased but in defence of my uni:
1) Somerset House is gorgeous. Google it for a picture, as I don't know how to embed pictures. But it used to be a royal palace! Does UCL have that? no. A couple of weeks ago we had London Fashion Week going on there, it really is the hip place to be.
2) Law dept = very good. This week we had Advocate General Jacobs lecture us. You might not have heard of him, but he comes up in European law and I've had to read lots of his opinions in cases for my tutorial. And the professors/tutors are very good. Some of them used to work at Cambridge, it's quite cool.
3) Maughan library is gorgeous. They filmed Dumbledore's office there!
4) Someone above said UCL could attract good speakers, but so does King's. Like last year I went to a lecture by Noam Chomsky, he was mentioned so many times when I was doing my English A-Level.
5) The Royal Family love us.... the Queen came to visit a few weeks ago.
6) King's offers a program where you can study at partner universities in Europe for a year. You apply once you're in the course. There are the likes of France, Italy, Spain, Belgium, the Netherlands etc!
6) loads and loads of extra-curriculars. I can't be bothered to go into them right now, but I have got involved in lots of law and non-law related activities. Whatever you're interested in, KCLSU have it.. like there is even a ukuele society?!