Any thoughts on Sky as a provider
The underlying Easynet core network (which they got their hands on via acquisition) is excellent
BUT I suspect you will only see the benefit if you are on Easynet's own branded DSL (which is targetted at businesses). I've got the feeling Sky's own product might be the same old rate-limited, packet-shaped stuff you'll see elsewhere.
UKOnline might be worth a look. They were an Easynet (long before Sky) acquisition and therefore probably of reasonable quality.
Otherwise, I've yet to hear a bad thing about Zen. Who I gather are well worth the slight premium price.
(Don't have any incentive to promote either of the above)