The thing is, it's not worth getting a generic one if you have a car from the VAG group. A VCDS cable is worth it's weight in gold. Not only error codes, but actual english descriptions of the problems, the ability to re-code modules (and keys depending on the car), and much more.
If you really want something that reads every brand then go ahead and get a cheap bluetooth OBD2 reader, but if you own a VW (or SEAT, Skoda, Audi) then really do contemplate a VCDS cable!
EDIT: I've just sent you a message to trust.