We've used both Coit and Stanley Steemer for carpet cleaning at different times. They seemed equivalent and about the same price, with about the same equipment. In both cases the cleaning was adequate but not much attention was paid to stains or problem-areas.
Coit did move all furniture and put small blocks under the feet, and they were polite and efficient. Perhaps a bit more professional than the Stanley Steemer folk, but that may be just variation of which truck we got. There was a bit of a hard-sell on some extra services. We wanted the stain resistent coating anyhow, but haven't noticed any difference with it.
The only real problem was the calls, in the evening usually, months later offering us "specials". Since they had my cell phone number, these were extremely inconvenient.