As john2007 says, Sky LLU is reasonably good. Just watch out for if they are full up though, as then they would put you on Sky Connect, which is BT Wholesale based like O2 Access but even worse!
If you take Sky Line Rental with the LLU Broadband then that is Full LLU where the line doesn't count as a "BT line" if you ever want to migrate out. That can be a nuisance. With Sky Calls but not Sky Line Rental it is Partial LLU which is easy to migrate from.
You can get LLU Unlimited, Surfwise Variety and Surfwise Complete from vivaciti
. The Surfwise Complete is Full LLU, like the Sky LLU + Line Rental above.
also offer the same underlying packages as vivaciti so check there as well.
Don't be tempted by Orange. New customers seem to be being put on BT Wholesale as well, as they are winding down their LLU.