We are a private label reseller for hostway, and they aren't the cheapest, but they are very secure and reliable, imho. I've gone with cheaper hosts in the past and have been disappointed- you usually get what you pay for, especially in the "support" department- god forbid something is going on with your site and you actually want to talk to a human about it. With Hostway I've not had any problems reaching someone on the few occasions it was necessary.
Their options for PHP/MySQL leave something to be desired, but I'm hoping that some day they'll come around 🙂 (for instance you can only have one database per client, and no "load data infile" allowed.. sucks for the developer, but like anything there are "work arounds" 🙂 )
hth-
-Elizabeth