If you are studying engineering I can recommend leeds. If you study law or buisiness obviously oxford or cambridge but you wont get accepted
London because it's their capital
I would personally go for Manchester or Liverpool
Oxford or Cambridge, UCL, Exeter, Bath, Warrick, Grenwich.
why the UK its terrible here
Birmingham, it has a bad reputation, but the uni is great and located in a safe place, amazing town center, lots of sport and public transport, is in the middle of the UK so can travel anywhere quickly - is cheap to live, 2nd largest urban park in Europe, home to the Balti Curry, digbeth raves, more canals than venice. Its like London, but cheaper, friendlier, safer.
Cardiff is quite lovely city
honestly it depends what subject youre going to study so id google something like "uk best university to study x" and then itll probably give you some comparison websites for grades and student satisfaction and all that, then id google the top 3 or 4 and see which one you like best personally so take a look at the accomodation and price of living and the night life and such. hope this helps :)