I've been using BT as as provider for business and domestic use since they started supplying the service (9 or 10 years ago).

I've never had any serious moans with them, and neither have I had a breakdown with the service. However - I do live on the outskirts of a city and use the same exchange as two major banking businesses. Probably that helps maintain a good service.

Whatever other provider you use - unless they use a cable connection, they'll be using BT's lines and cabling to your house.

I've not had any problems with the wireless side of broadband when I've used it, but I happier with cables.