I think a lot depends on your individual hair type. Hairdressers also have very individual opinions on the good cheaps and the bad cheaps (IMO).

My hair gets 'bored' with shampoo quite quickly so I have a few different brands sitting around at any one time heh. I have my more expensive KMS and less expensive Fructose and I think I even have some budget V05 because the conditioner just works for some reason...