I really wouldnt know mate, ive never had too much bother with BT, always just accepted my lines as is as ive never been fortunate enough to have one thats any good
As far as routers go if you can get a belkin 7633 v1001 then go for that, the newer v1144's are useless as they are all locked down. These contain a rather excellent broadcom chipset which allows for overiding the DSLAM's set noise margin for your line so you can play about yourself with sync speeds rather than letting bt do it. I know that there are a couple of other which share this chipset one being an 834GT netgear, but overall none are renound for being quite as good. There is a noise margin tweak available for the latest range of thompson routers too.
Billion's latest offering is supposed to be great too according to a guy i chat to about dsl things on msn, he knows his stuff dsl wise so i'd trust that choice too.
If you are considering max on a dodgy line like yours and mine the router is VERY important indeed, as i say changing and tweaking has almost doubled my sync rate.