That depends on a whole lot of factors and your personal preference.
Think about location - do you want to be in the busy, social area of London, or would you prefer to be elsewhere? Cost of living comes under this: would you be able to stay at home and save money if you went to a certain uni, and how expensive is it to live in each of these areas?
The content of the courses - what differences are there in what you'd learn from uni to uni, and are there any modules, topics, ect, that particularly stand out to you as being of interest or not of interest?
The social aspect of uni - is one uni more well known for being social than another? Which scene would you prefer?
If all else doesn't help narrow it down, you could always pick based on the prestige of the uni or course, but just because it's a 'great' degree or uni doesn't mean it will be great for you.