I'd always recommend choosing your college by room type first, then the distance to your department. I think the size/type of college can also be important if lots of colleges are offering the same rooms. For me, I've loved being in a smaller college as it feels a lot like a little community, but I know others who prefer a bigger college as there are more opportunities to meet like-minded people. Some colleges have a rep for being sportier than others but this changes over the years - used to Fylde, now its County - so I wouldn't worry about that too much.
I wouldn't say there's any difference in the sociability of colleges really, although I have noticed in some colleges ensuite accommodation tend to mix a lot less. I think that is just down to who's in the flat though, so that's very hard to predict!