there are rumours that JKR's Hogwarts was based in part on the University of Glasgow , (and a bit on Heriot’s School in Edinburgh)
that's not very relevant, but I have had two friends who did undergraduate studies at the very prestigious UoG, and two friends who did their undergraduate studies at the very prestigious St.Andrews - one of whom then went to UoGlasgow to do her MSc. So you could end up at both, eventually!
You didn't mention which subject, that might be important. I'd bias Glasgow a bit better for Sciences, St.Andrews a bit better for languages & similar.
Life, wow, St.Andrews is a mini Oxford college, just the one, in a seaside location, drier than Glasgow - still a bit windy. Gorgeous location, impossible to get into. they have a really nice partnering system where each new student is given an older student 'college parent' as first point for solving all the small problems. they are very friendly, it works really well. the sport of Golf was invented nearby, in case you like that sort of thing.
Glasgow, wow. it is a mega city. everything happens there. amazing place. Big University, very prestigious and hard to get into, too.
Aberdeen is great but v e r y f a r aaaaaaway