It really doesn't matter. It's not like you're comparing Oxford and London Met, these are three good, respected universities of similar calibre. No employer is going to not interview you because you went to Warwick instead of UCL. It's about what you do with your degree, it's about the connections you make, it's about experience. The majority of TSR users seem to have this impression that employers have this ranked list of universities on the wall, and you can only get a job by going to _____ University (funnily enough those users are usually A-level students, not people who have actually graduated and started looking for employment).
Go wherever you will feel happiest, not the place that has a minutely better 'reputation' because it won't make the slightest bit of difference. What will make the difference is how you perform at university, and that will probably be a factor of your happiness.