I like to think I know a fair bit about cleaning carpets, but I can't understand your question.
What exactly do you mean by "a reliable carpet cleaner"?
A way to clean stains out of carpets without using a carpet shampoo'er?
A carpet cleaning machine that you can rent other than Rug Doctor?
A carpet cleaning machine that you can buy?
A good carpet cleaning soap to use in any carpet shampoo'er?
Maybe just explain the problem you're facing as there may be other solutions than to rent an "Easy Off" machine instead of a "Rug Doctor" machine.
Also, neither "Rug Doctor" nor "Easy Off" rent good quality carpet cleaning equipment. Nothing they rent is comparable to what your local carpet cleaning contractor will be using.