There is a guide on this somewhere...
Personally, I like Tocil best. I was there in my first year (applied again for final year, but didn't get it!) and it is reasonably priced, very central on campus (next to gym, near union and academic buildings) and the rooms were OK too.
To be honest though, if you asked all current first years which accommodation is best, I reckon 90% would say their own one! You'll have a great time wherever you are.