I've used all of them, I like cPanel's X3 theme and their latest design is un-user friendly. Interworx hasn't changed since I used it and it's okay to use, DirectAdmin is a bit more user friendly than all of them and they never used to have a nice design. For example back in the day if you used DA you could be editing a file and accidentally click off the box and it would close and you'd loose all your edits / hard work, but that's changed lately for the better.
I personally prefer DirectAdmin in this day in age, or pure SSH. DirectAdmin is affordable and they've improved it.