I'm quite a university snob and I wouldn't class UEA as a bad uni. It has a really high reputation for individual subjects, such as English, but the OP isn't studying English, er, so, yeah...
To be honest, I think the course is one of the most important factors. At the end of the day, uni has a lot of perks, but you are going there to get a degree and getting that degree depends on you doing well in the course. And if you don't find it interesting, don't turn up for tutorials/lectures etc, it could be difficult to do well.
Whereas if you are motivated, enjoying the course, passionate about it, the chances are you will not only do well, but be generally happier as a result.
So, in that respect, I'd say Durham (if it is more attractive to you as a course).
You must also remember that Durham is fast becoming a top uni, or indeed, is a top uni, in Top 10s for most subjects now. It has a wonderful reputation and is much sought after.
However, from what I've been told, Durham is quite a quiet place, so it might well be that you’d be happier somewhere a bit more…sociable. Although I don’t know first hand.
And, yes, the weather is better in the UEA. But I’ll tell you where the weather is even better…Australia! That would be a big draw for me, definitely!
I empathise, anyway, I’m crap at decision making. But at the end of the day pick where you think you will be happiest, and not where you think prospective employers/your friends/family will like. At the end of the day if you’re not happy, life is ****.
(Pssst, Australia!!!!)