BT are not really any better than the average providers Ive come across .. bear in mind they have no control over BT openreach which is a separate company., that provides the broadband infrastructure should you have a problem. Ive been using Zen internet for about 8 years ... brilliant service but not the cheapest, I cant get any cable services here like virgin, although I can get fibre to a cabinet near me through Openreach.
The big thing about Zen is they have a very big stick to 'beat' openreach with ... and if there ever is a problem, which is always openreaches fault, its sorted in jig time
Even BT cant get openreach to move that fast Ive found
Oh and I should say ZEN dont throttle or traffic shape like Virgin do so your speed is always what it says on the tin