I'd go for UCL as opposed to LSE. Yes, perhaps it's slightly less 'prestigious', but it's still a damned good university (and still very much targeted by top firms for recruitment) and you will have a substantially better time, given what I've heard from LSE students (or ex-LSE students who came here for postgrad). In any case, nobody REALLY cares about 'prestige', especially if it's such a tiny gap as LSE vs. UCL, when you're actually doing your degree.