Very hard to say. Depends on what you are looking for and whether you are looking for undergraduate or postgraduate.
The universities in London are great because you have access to all the facilities that being in the capital gives you. Lectures, libraries, exhibitions etc.
My favourites for Part 2 are University of Sheffield and London Metropolitan.
Have a look at the information from the RIBA here:
Have a look at these comparison tables but be careful because they hide the particular things people find interesting about certain universities: