I use MediaTemple and Slicehost. They are both excellent. Support at MediaTemple is impeccable although they have had significant downtime and it is starting to get annoying.
Great for very user friendly, dead simple web hosting. They are very clear about downtime and future upgrades.
Support: Always great; I have called their support line on a number of locations and they were extremely helpful, easy to understand, and very friendly.
Excellent root access, bare bones virtual private server. I have had absolutely no problems with them.
Support: I have never had to call Slicehost and have only been in their online chat once (to ask some server administration questions). I hear that their support is great. They have a number of people accessible on Twitter who have answered my questions instantly (Robert Scoble now represents Rackspace).