CB Subs (free and paid) just works. I am a fan of this component and the people behind it. It's running two non-profit orgs, flawlessly.
Ease of use
Insanely comprehensive and intuitive. The 650+ page manual is a beautiful beast!
There is not score high enough for the support staff. I cannot imagine how crazy it must be and yet they are polite and sooo helpful.
As mentioned, the manul is 600+ pages. It's incredible to see and experience. Plus they have great videos to help if you need more.