i think rackspace is quite good, they seem to have good reputation and experience in datacenters and hosting. personally my experience with them has been with cloud servers and i think they're making lots of investments in this space, overall the price and ease of use for their cloud server is quite impressive. i think they use xen for server virtualization, which is a negative in my opinion, but the management interface is quite good, i had my debian lenny image running with ip in less than 5 minutes.