I'm a third year but was in Alcuin for the first. Based on accommodation I don't think you can find any better at the Uni, but the college is severely lacking socially. Don't be fooled by the Alcuin bar 'B Henry's', the only time anyone uses it is on the very first weekend when everyone is meeting and greeting. Apart from that it's a ghost-town that only has limited open hours and limited drinks. The people are all great, and obviously at every college you'll find like-minded people who you go out with, but Alcuin certainly isn't some kind of party college. A flet of my flatmates and I would go out a fair bit, and obviously you can go out with sports teams/ people from your course, so it's not just based purely on the college. I always loved having a big night out and then returning to my ensuite (which came in very handy in the morning! Imagine running back and forth to the shared toilets hungover). Derwent is probably the best college to join if all you want to do is to socialise, but the accommodation there leaves a lot to be desired, so it depends what you're after.
If I were to reapply again, I'd definitely choose James College. It's the best of both world. The majority of accomm. is very nice and similar to Alcuin standard, apart from the unlucky few who get dumped into one of the older buildings. The social life is good and they have a nice new bar that's been refurbished, plus it's very close to the sports centre and you feel like a part of the Uni, at Alcuin you're well out of the way from the university hub.