I don't work for either of those universities so I don't think I can answer your questions without being very biased! I would recommend looking at the showreels of graduates from both universities (find them on Youtube) and compare them. Look on Linkedin for recent gradautes and see what companies they work at and aks them if they think the course was worth the money? Also 'better' is a difficult thing to define; it would depend on the type of animation you want - I can't say one is better than another; I would say that BU are more known for VFX / photorealism, whereas AUB are more known for stylised work, but that's just my opinion!
Regarding Leeds I do know the lecturer who runs the Concept Art degree and she is very talented - what the university is like for art in general is something I don't know (I haven't visited Leeds University for over 30 years!) My memory of it was it has some lovely old buildings and a huge library, but that's not much to go on, sorry - maybe ask in the Leeds University section of this forum?