o2. Period. Consistently the fastest performing network, confirmed fastest ADSL ISP (was the fastest ISP in the UK statistically until recently when Virgin Media narrowly took the lead), awsome 24/7 freefone customer services, fastest Upload
speeds of any residential ISP by far
, rediculous pricing, uncapped/unrestricted service etc... also some cracking additional features that offer additional value such as email-text which is pretty cool (especially for myself with my business).
If you need higher download speeds however, and your far away from the local exchange, you may wish to consider Virgin Media if you are on their network, as their technology does not suffer from distance issues. Though they do severely shape traffic, have some network and backbone capacity issues, restrict high users at peak times and do not offer net neutrality. And their customer services is poo. Heavy uploaders may wish to steer clear, as their speeds are well below standardin relation to thier download speeds, and the DOCSIS cable technology that they make use of, is not suited to heavy/fast uploading.
For an ongoing long-term review of o2 Broadband, by myself and a few other members, click here