(Original post by Starkadder)
If you're looking for international rep (as an American student, maybe concerned about how your degree with travel), then I'd have to say UCL wins it.
My girlfriend (PHD student in Durham, undergrad at Cal, Berkeley) attended an event the other day with Bill Bryson aimed at trying getting ideas to raise the prestige of Durham in the USA so it can compete with St. Andrews, UCL, etc. it's certainly an issue the University is aware of, so who knows what will happen across the next few years.
As for which is a better 'student' experience, I have friends at both who have enjoyed their time. Durham gets called 'collegiate' but it's really not in the sense that Ox/Camb are: more you simply retain an affiliation to your hall of residence after you leave (plus they all have bars). I think it gets called 'socially collegiate'. The upshot of this is that making friends at either will be easy enough, so I wouldn't take the whole 'collegiate' argument too seriously. In London you'll be in a big city and have access to all those amenities, Durham will have more green space.
Durham does have a bit of a rep. in the UK for attracting bitter Oxbridge rejects and some pricks, but as any student there will tell you you get twits everywhere and most students at any university are going to be fine. UCL has a bit more of a hippy, left-wing rep (it often reminds me of a UK version of Berkeley), but again, take this with a pinch of salt.
In general, if anyone tells you hands down that either UCL or Durham has a better rep within the UK they're probably grinding some sort of axe.
People will talk about the 'G5' or even 'Doxbridge'...
(yes I know it was originally a sporting competition etc. etc.), but basically below Oxford and Cambridge, the top 10 (ish) UK universities are pretty much even.
A note on subject league tables. I'd ignore them. Unless one of your universities is ranking well below another, they're largely pointless & simply provide ammunition for people to grind their various axes on forums like this. Unless you're looking at the sciences and wanting to go into academia / research, provided a department is coming in the top 10-20 and has a good student satisfaction don't worry too much. In terms of career prospects, no employer is ever going to care that [insert university here] ranked above Cambridge for English in the year you applied... overall rep is a far better indicator and UK-wise they're pretty even (although UCL is certainly more world renowned
Hope this helps. TSR is a huge hive of wobbling insecurities so try to ignore any posts that don't substantiate claims. It also is mainly driven by high school students who have little experience of the Universities they're talking about! If I were you i'd look at the modules offered by both & see which you like the look of more! Personally I'd pick Durham for quality of life / cheaper accommodation but London for employability / academics. It won't matter too much either way though.
Also - I should add, I'm a student at neither (although I had offers from both back in the day, visited them and have friends who chose to go to each).