So if you want to be treated well you are probably best just to sit in your house with no services
BT and Sky in my experinece wont treat you any differently. Big companies equal crap customers services its life. I havent dealt with any big company who can offer me better than sufficient Customer service. If you try to upgrade either your BT line or Sky package from work and didnt have your details you would be treated exactly the same.
Having sample the grass on either side of the fence there is really no benefit in switching providers other than a minor cost difference, a a little personal preference.
The only difference with Sky is you will pay for the 0870 call