Both are great for Law. Mile End isn't that bad, I've been in worse areas. For better or worse, a lot of the 'rough' parts of London are being gentrified.
Durham would be the better option unless you don't like the collegiate system or want to be in a major city.
I saw Bristol pop up earlier in the thread but didn't read it properly. Bristol is also very good.
Unis that I know are generally renowned for Law are Oxbridge, LSE, UCL, KCL, QMUL, Durham, Bristol, Nottingham, Warwick, Bristol, and a few others.