Durham firm, Notts insurance.
Rep with employers. They're all good, can get you to the top firms.
Social life -- I mean, that is difficult to answer. Exeter is a small city which is really a town, and Durham is even smaller (but Durham has colleges which provides a lot of your social life). But you can be as social as you like wherever you go. Newcastle is the bigger party citaaah. Regard the unis -- all pretty decent.
Why I'd pick Durham is that it has the most rigorous academic experience because it has the brighter students. Notts next. Durham also gets a lot of attention from firms, has a lot of people making it to firms and being proactive around you -- so your path is a little smoother as you can replicate what your peers are doing, but you can get there with any as they are all extensively visited by the top firms and have proactive kiddos.
You have to think about missing your offer by a coupla grades, AAB. Would Notts necessarily take you and where else would you go? Bearing in mind if you get AAA, i.e. Notts' offer, Durham might still take you. So maybe the other three might be better as insurance, as they're all really gonna take many AAB students on results day. This should impact your decision depending on how confident you are in meeting your offer.