It doesn't matter too much where you live on campus, you can get pretty much anywhere on campus within 10 minutes and there are regular buses that run between the 2 campuses that are free within the university. It can be convinient to live in a college on the same campus as your course but you wont have to spend too much time getting between your flat and lectures. Lots of the rooms are almost identically similar to the other colleges, so the only difference will be the location.
All of the accommodation is pretty nice, even the cheapest options. I lived in Alcuin in my first year and Vanbrugh in my 3rd year (both were ensuite rooms) which were both some of the more expensive rooms and were very nice and the kitchens (especially in Vanbrugh) were spacious and fairly modern. My friend lived in the cheapest block (James N block, affectionately names prison block) which was obviously a lower standard than mine but it was still liveable. The kitchens were much smaller and shared with more people but the block was catered and the shared bathrooms are cleaned every day and worked out at 1 toilet to around 4/5 people. I'd probably say that the worst part of that block is its right next to the lake so you might get woken up by the geese.
If you enjoy living on campus its pretty easy to stay on if you apply early enough and you'll be placed with returning students so it will be much quieter, although private housing off campus is much cheaper. I've gone from paying £140 a week to paying about £80 a week once I factor in bills from my 3rd to 4th year, just make sure to try and avoid any dodgy landlords/letting agencies.