Broadband-internet providers? bt or sky broadband?

I have had bt broadband for 18 months now, the service has been ok but nothing spectacular for the speeds we are always hearing about. sky broadband is a lot cheaper for (apparantly) the same speed, but does somebody reccommend bt or sky in terms of thier speed and reliability, as these are my main concerns than the cost. any advice would be great. cheers.
Answer
I have sky in one home and virgin ntl in another home, both are fantastic.virgin ntl goes up to 10meg speed you have a choice of 2, 4 8 or 10 megs depending on the price speed is dependent on factors, my 10 meg was 7 meg when tested. it is fast they have a great service, had to pay extra for a 4 line router whereas a wireless 4 line router comes free with sky.sky goes up to 16 megs dependent on your local bt lines exchange. you have to have a bt line for sky broadband, my speed is blisteringly fast, i have not tested it yet but you know, when you know it is fast.sky is definitely much cheaper especially when you have the movies and phone included, i have sky (x 2 dishes) sky sports, broadband, free phone calls to most of the world and uk (extra to mobile phones) my bill is 36 pounds a month plus seven pounds per month for the bt connection. it works out three or fouur hundred pounds cheaper then virgin.now bt is good but i found then to be mega expensive for everything and you cannot get movies with bt,i have had both systems since march this year, i would advise you to go with sky for speed, quality of service and much cheaper prices. virgin is still great .i have been used to 2 meg speeds with att and sbc in the usa for years so what we have here in the uk is superb by comparisson and cheaper ..