I've used Rackspace, Amazon and GoGrid. I'm currently almost entirely on GoGrid and just finishing up migrating back off of Amazon for the second time(Migrated

I've used Rackspace, Amazon and GoGrid. I'm currently almost entirely on GoGrid and just finishing up migrating back off of Amazon for the second time(Migrated some services back to them when they opened west coast). There have been some stability issues in the past year(instances going down for maintenance regularly) but haven't had a problem with that in a while and was advised it was due to them upgrading all the servers in their cluster. The ability to mix dedicated and cloud systems easily has been the killer feature for me. We also prepay and the number of servers we get for the cost is pretty good.