I recently changed ISPs for my home network. I now use O2 (in UK) O2 bought Be Un Limited a while back. I was on Sky - Sky bough Easynet a few years ago. Sky was very slow and unreliable.
The upload bandwidth was almost no-existent. Experience playing on-line games was not much fun due to the lag. You need good upload bandwidth for playing on-line games successfully otherwise you just get slaughtered.
I used http://www.speedtest.net to measure the speed of both networks. As you can see, it is a big difference between the two networks. Also notice the ping response differences.
Anyone else in my area, Guildford, South East England who is on Sky should consider O2.
Here are the results:
Sky Easynet (before)
O2 (Be Un Limited)
I am around 5 miles from the BT exchange.