I actually go to a sixth form college, it was one of the best choices I've made in my life.
I remember I had applied to this college but I'm so glad I rejected it, the people there were underachievers and the people there just weren't nice. The people in my sixth form college are better academically so it meant I would more likely to do better in my course too. Also the people were more mature and friendlier in general. (Plus it's only 2 mins away from my house)
I'd say go somewhere you know you will do well but also take account of the environment you will feel comfortable in.