I'm going into a studio for my 3rd year. I'd imagine a decision depends on how introverted (or extroverted) you are. Even me being quite introverted and anxious, I'd imagine a studio would be very lonely at times for me, but can be mitigated just by going outside and meeting with someone or going on a walk (at least for me). For me it was a tradeoff between potentially awful flatmates or an isolating living situation, for me I find it very hard to concentrate if I'm constantly having to deal with flatmate drama/noise. For the sake of my grades, I choose the latter. Also unlike you my 2nd year experience in my house was downright depressing, it was dysfunctional because nobody spoke to each other except the odd time in the kitchen for 2 mins or on the facebook group. The two girls got very cliquey and made the house a downright hellhole to live in, which negatively affected my grades and happiness. I can't wait to move into a studio personally.
If you're the type to really relish having people around I'd personally risk a houseshare or new halls flat, but again, what if you get terrible flatmates or noisy first years? Only you know really.