We ended up with Tiscali (Talk Talk) but there isn't a great deal of choice where we live, and their ADSL has been fine. It's not very fast, but around 1.5 Mbps on the download - on a good day - is about average around here, and it's sufficient for us. The only snag, in several years, was a service outage that was a nightmare to resolve. Endless phone calls, "consultants" who didn't understand English very well and hadn't a clue what to do, lies about the cause of the problem, and meaningless promises; just to get you off the line. I finally got one of their more senior people, and she sorted it out in no time, but it was a struggle getting there.
I wouldn't pay too much attention to the speeds the service providers cite. These are just the maximum speeds you can theoretically achieve, not the speeds you will actually get, and they're not part of the agreement. There have been a few suggestions that government will intervene and force the service providers to be more transparent, but I don't know where that will go.