What are some good carpet steam cleaners?

As of 2015, Amazon.com reviewers give the Hoover SteamVac Carpet Cleaner with Clean Surge 4.2 out of five stars. Target reviewers give the Bissell ProHeat 2X Revolution Pet Carpet and Upholstery Deep Cleaner 4.7 out of five stars.

Reviewers of the Hoover SteamVac praise it's cleaning power, with one reviewer claiming it works as well as a commercial steam cleaner. Negative review points include slow cleaning and leaking. Target reviewers say the Bissell ProHeat unit works very well on pet stains, is easy to use and light-weight. One reviewer warns that the color from the red cleaning bristles bled onto his carpet.