I use aDSL through Timewarp (
www.timewarp.co.uk) and I've found them to be excellent. I've been with them for over 6 months now and I've not had a single problem with them - it is always on as long as I want it, it never drops, well it has once or twice, but that's not bad, and it comes back straight away. I never seem to suffer from lag or slow requests and quite frankly I'm very impressed!!
Unfortunatly I signed up with them on their full service package, mainly cos wires only wasn't available way back when, so I'm paying a fair old chunk for the serivce, but it's worth it. I think so anyway!