InterWorx is a very effective take on the modern web hosting control panel. It easily allows access for admins, clients, and clients of clients to manage anything needed for their environments. Additionally, it has useful features such for managing domains, email and websites suited for system administrators and web masters.
NodeWorx and SiteWorx
Through email and ticket system
Continual product upgrades
Annual or multi-year pricing
Phone support whenever needed
Higher prioritized input on product roadmap