Do you need a fully managed server, or are you capable of managing it yourself. Does the location of the server matter to you (i.e. East Coast, West Coast, ...)? With $400 you can get a lot of server and most of the providers you listed are budget solutions.
For managed/semi-managed servers, have a look at the following:
(they offer WHT members sizeable discounts)
For unmanaged servers:
(highly recommended and they do also offer managed services if required)
Hope that gives you a start.