I would like to know what is considered the best portable machine for cleaning carpets. I have used a Rug Doctor wide track and did not find anything to complain about but not sure I would know what to complain about anyway. Also what is the single most important feature to look for in a machine, is it the holding tank, how hot it gets, or RPM's of the motor? Oh yeah, I tried to search for similar topics but I do not have that permission.