Vis a vis study area's in Balliol - Balliol has some dodgy dodgy rooms. It also has some lovely rooms. It all depends how you do on the ballot in third year. First year you'll get the leftovers from whatever price band you choose - cheap ones are the fresher rooms in the 60s ghetto, fairly basic, like most unis tbh, more expensive ones are more likely to be leftover third year rooms, which might have bathrooms, study areas, sofa depending on how third year has chosen. Second year you live out or in Jowett, but rarely on the mainsite.
Balliol's bar is nicer and friendlier than Trinity's. Trinity's food is a lot better than Balliol's.