I've been using Doc's of Denver Carpet and Upholstery Cleaning for about four years. They are responsive when you call and make appointments. Recently we had an extremely snowy day, and they still made it out for the appointment. Nobody knew it was going to snow, but they still made it and got the carpets incredibly clean.
They did a great job! There's huge difference. I've used them numerous times, and I continue with them because they get stuff out of the carpets no one else has. They really concentrate on getting the carpet clean, and they don't try and sell me services I don't need. The work doesn't take very long, and I can tell they work very hard.
You should go with Doc's! They may be a little more expensive, but it's worth it! They have exceptional quality.