I know you're looking for alternatives (rackspace might be worth a look), but I can't say enough about MaxAsp. I've had 4 servers with them for a few years now and wouldn't think about going elsewhere.

I just did a similar search and went with HostMySite.com.  I chose them over MaximumASP because I wanted a VPS, not a full dedicated server & their offering there was better/cheaper.  Like you, my other focus was on customer service, reliability and long term viability.  All the research I did uncovered several articles on how they are profitable (for 8 yrs I think) and how they were formed around high customer service.  Their CEO even has a customer service BLOG and he has been interviewed several times on his customer service approach.  They also have dedicated engineering staff for the dedicated servers.  I think they host 80,000 domains or so and they are based in Delaware.

I've only been with them 2 weeks so time will tell.  So far, customer service has had no wait time the 3-4 times I've called.  You may want to add them to your list of ones to research.