I've been a customer of thinkhost for about a year now, using their shared hosting. From the moment I signed up with thinkhost, I have been extremely impressed with their features, ease of use, and customer service. I have had a couple different problems (almost always of my own causing), that they have kindly and quickly helped me solve.
I am a big fan of their ticket system after being forced to pay to be put on hold talking to some Indian lady who didn't know anything (OneandOne), or being given the run around by Startlogic's terrible e-mail support where every e-mail I sent would go to a different customer service rep who would have to ask me the same questions all over again. I literally e-mailed with over 15 different customer service reps from Startlogic and each one would have to start over from the beginning with my problem...
With Thinkhost, however, whenever I submit a support request ticket, I get an e-mail back within an hour or two, and usually my problem is solved shortly after that. The longest its ever taken was until the next morning. Compare that to Startlogic, which took 7(!) weeks to solve a simple problem.
With their features, service, and commitment to social responsibility all for just 8 bucks a month, I don't see how you can top Thinkhost...