I've got BT Infinity, highly recommend it. You have to have a phone line, but doesn't mean you have to plug a phone into it! If Infinity is not in your area then you're stuck with ADSL.
If you're not in a cable area, you don't have much other choice. Tethering, whilst it may work, will likely not be very reliable (in my experience anyway), depends what you want to use it for.