Its very hard to say, as all cater well in terms of their events. I would disagree that there is any specific college that has a better freshers but the main differences occur afterwards.
Goodricke have the reputation for putting on big events, hosting a 'goodfest' each year inviting a number of up-and-coming DJs and musicians, as well as a few other things, but they lack in the number of smaller stuff.
Vanbrugh have a track record of bad budgetting, last year a misjudged formal event lost them £12,000. So don't expect their events to be the best, they are however sort of back on track and their freshers is still good.
Langwith have a reputation of good management and organisation. Their freshers and events throughout the year run very well and they have the coveted title of Committee of the year in this regard. Though of course that committee is no longer the same one that will organizing your freshers events!
Derwent has strong humanitarian links, owing to the fact that it encompasses a number of their departments within its boundaries. Allowing it to offer a number of volunteering and personal development events, but they also have a brand new, very expensive sound system and aim to and have already put it to good use. So expect more festivals from them, their accommodation is unfortunately still stuck in some sort of an amalgamation of the sixties.
James is near to the sports center and can boast more sports oriented events as a result and haven't got a bad set of events either, however they are bit more spread out as a college.
Alcuin are very professional in the way they manage and do things, and have a good calendar of events throughout the year. But lack a certain regard of community outside of their own, which is strong. They are a little out of the way though, and so it is a bit of a slog if your department isn't close.
Halifax is not as bad as has been exaggerated. The accommodation yes isn't the best, it is like Alcuin a bit out of the way and it is by far the biggest college but it has got a strong sense of community and has a great set of events during and after freshers, considering the fact that they have to cater to such a large population.
Constantine is the newest college and therefore has never hosted a freshers before. As Secretary of the college committee though, we see this as more of a blank canvas where we can build upon the mistakes of other college's and make sure that it encompasses a strong community and modern approach to university life; enjoying yourselves! Being brand new does mean that our college budget may be slightly larger, the accommodation being brand new and quite nice, the center building being made almost exclusively of glass panels with nice high ceilings, a balcony and a piazza out front.
It is very much up to you and what you think fits you best. I would say though that whatever you choose there isn't too much that can go wrong.