DreamPress from Dreamhost excels in support quality, has good performance and is an attractive offer for Managed WordPress hosting. However, it lacks some advanced features and only hosts on US Datacenters.
GridPane is a very promising control panel with great performance, good usability and friendly support. It makes managing WordPress on your own VPSes a breeze. However, it still feels in development. It's particularly worth the value if you are managing multiple sites and servers.