Thanks to everyone who's replied! Based on the responses I've made a wee list of reasons to choose both unis, here it is:
Edinburgh
* More prestigious -> helpful for employment/further study
* I'll probably fit in better with the student body
* More/better facilities (presumably)
* More interesting city, more to do, better transport links etc
Aberdeen
* Better course rankings (not sure whether that'll be any advantage at all though)
* Campus uni
* I like the course content better
* Staff seem more friendly, it all seems a bit more personal, I liked the overall "feel" of the university much more than at Edinburgh
Based on this list, which uni do you think I should choose?