These are my own personal experiences:
Using Virgin at present and it is simply incredible, great customer service and its been a dream in comparison to other providers, yeah paying a little bit more but now on fibre and its freaking awesome.
Had a poor experience with BT in the past, and an even worse one with Talk Talk. Talk talk was cheap mind and if you are not dependent on a very reliable connection its worth considering but I do offer a warning.. Should things go wrong, you end up calling an Indian based call centre who do nothing but read from a script, they are utterly useless in resolving problems, often insulting, and when calling them for the 50th time and they start from the script again I can tell you, you are going to freak out.