I pay for 256 DSL, I get 1.2 megs usually. I know people on the same service a few tonw over who get 256 and that's it. All depends, same thing with cable. If you pay for one speed, that may be all you get, or you may get more.

Cable of course has much faster uploads, my upload speed is like dial up speed.

Reliability is more a function of the provider then if it's on telephone line or a cable line, speak with your neighbors to see how the area companies do. I know my DSL is up way more then cable is in this area, it's one of the reasons I've stuck with it for so many years.