In terms of providers... it seems everybody has a different opion, NTL and Wanadoo have a really bad reputation but I never had a moments problem with either of them (over 5 years), however when it went to Orange Broadband it was rubbish.
Again things may be different these days but AOL always had a bad reputation, if for nothing else than it installed all sorts of crap on your PC. It's similar with BT, my dad for example has BT broadband it installed all sorts of rubbish on his PC. I just got BT broadband at my new place but refused to install anything (as it is unnecessary) and it seems to work fine with my current (Belkin MIMO) router without having to install a single thing from BT.