As Mad Penguin suggests, other than how crap support is with commodity ISP’s (and obviously the speed difference between fibre/copper) … they are all much of a muchness.
Decent support costs … but then on the whole broadband is pretty reliable anyway.
I’ve been a year on Sky Talk Anytime + Unlimited Broadband (copper) … and though I too dread having to resolve an issue via Indian call centres … so far it’s cheap, reliable (apart from twice in the last year when just broadband went down for 15 minutes, still dunno what that was about, and oddly both times at 00:30 exactly), and does what it says on the tin.
Prior to that I was with Pipex … who were very reliable until taken over by Tiscali/TalkTalk, then broadband was down as much as up, and they always blamed BT’s line … funny how the problems only started when they took over ???
Proir to that I was with BT … never had any issues
Prior to that … Blueyonder (now Virgin) … no problems
Prior to that … Demon (dial-up) … no problems, as far as dial-up went 
Prior to that (first ever internet connection) … AOL … NEVER AGAIN, not only immensely unreliable, but when I quit, they stole £600 from me … long story.
Suppose I’ve just been lucky as far as broadband goes (touch wood).
[EDIT]
@ BkS
BT and pretty much all other ISP’s will charge a fee if the problem lies on your side of the primary test socket … if it’s the other side (ie. outside your house), you shouldn’t pay anything.
(service is ONLY supplied to the test socket … anything after that is considered YOUR responsibility)
The only thing I don’t like about Sky is that you HAVE to use their router … that’s part of the contract … not that I’ve had any problems with their router, but it means if it ever goes wrong I’ll have to buy a new one from Sky (they’re reasonably priced, but it aint gonna be just a trip to the local PC shop).
.