As mentioned before, there are only 3 true collegiate universities in the country anyway, so you will have to apply to a mixture of other ones as well!
As someone that is going to a collegiate university next year (Durham) I have to say that for me, it was one of the strongest pulls. The level of community and academic supervision you will get is unrivalled (this is particularly true and Oxbridge, but still true at Durham). It also gives you chances to participate in sport, drama, societies, committees that you might not get in another system.
That said, there is a danger of falling into the collegiate bubble, and socialising with the same group of people time and time again. However, it will be much easier to make friends in a collegiate system than anywhere else.
Oxbridge and Durham, however, are not renowned for their nightlives. So if you are a bit of a raver, then they might not be the place for you. There are only 3 clubs in Durham for instance (one of which was voted the second worst in Europe, and the worst has since burnt down), there is Newcastle nearby though. The nightlife in Oxford is actually alright, it is a proper town and therefore is more dynamic than Cambridge, who's best club Cindy's is simply awful.
A city university such as Bristol or Manchester, will be much more vibrant in terms of nightlife. As will London, where you should effectively regard the different colleges as separate universities. So it is all a question of priority. I want a life where I bike round small cobbly street, go to pubs and formals etc..and participate in collegiate events. Others want the clubs and bright lights of a big city.
Those are the essential differences.