When I applied I concentrated mainly on location (thinking I wanted to specialising in Physics though, so now totally the wrong end of town...), accommodation (or at least the very limited range of rooms shown on the open day, which was basically just the nicest room in every college) and I have to admit statistics (coming from a state school background with parents with very little knowledge of the university admissions system despite having really good grades I guess I still didn't feel confident enough to apply to some of the other colleges which may have suited me better).
Murray Edwards also had a much stronger focus on careers, with weekly workshops and exclusive internships which really attracted me to the college. Unfortunately I didn't research thoroughly the accommodation costs and options (despite most of this info being online) since I was under the impression that they were really the same between colleges (I went to a standard state school, so this was based on what the admissions officers/ students who gave us a talk told us at some point). I'd say Murray Edwards is great if you're very career-focused, like free holidays (we have awesome travel grants/ scholarships), enjoy more relaxed/ pretty surroundings out of the centre of town, and aren't so worried about saving money (they'll always make sure you can afford the accommodation, there are hardship grants etc. available if not, but if you don't want to spend all of your loan on basic living costs it's not so ideal...).
In hindsight, I wish I'd considered costs and accommodation more, couldn't have done much about location except realising how much I hated physics earlier, and I really shouldn't have bothered worrying about statistics. If you're good enough to get in, you'll get in, no matter where you apply.