Started using Keystone Carpet Care on the advice of our Realtor in 2009. We bought a foreclosure and wanted to make sure the carpets were clean and ready to go when we moved in. They did a great job, including dying a bleached area to match (you'd never know it had been damaged to look at it now, 5 years later!) without extra charge. Have had them back every 6-12 months since and they always do a great job. On time, friendly, professional and leave my sad builder-grade carpet looking like new.
They may cost a little more (I don't even know since I don't bother taking a risk with another company) but I've never been disappointed.