We use Helm 4.
Why we use Helm 4?
1) Firstly it allows you to develop your own modules and language packs unlike most control panels.
2) Secondly because of the unbeatable pricing in comparison with other contorl panels
3) Thirdly because it has an inbuilt billing system
4) Fourthly because of the automation of the control panel unlike other control panels
5) It is one of the only Carbon neutral control panel
6) We have many other reasons we are using Helm, most of them can be found in their website:
http://www.webhostautomation.com