KiCAD is the absolute best tool in the world for the price.
It has features that will rival most paid software packages, in some cases it does it better, for others it doesn't.
Diptrace, like EAGLE, are pricey in comparison, although not as pricey as some other packages.
If you use these packages commercially you will be more drawn to them for home use and then it can seem a bit expensive unless you can use a work license at home.
Now, imagine using KiCAD commercially, you find a bug, you report it, 2 years later it MIGHT get fixed unless you can fix it yourself (note: Most users can't fix bugs).
Where software like Diptrace will outperform others is in support, you can manage around "features" or chose to pay for extra features, but you can't generally manage around bugs and support, waiting a few days for a bug fix costs enough, waiting years costs a lot more than your $600 subscription!
If you spend all day using Diptrace, EAGLE, or Altium, you're going to naturally want to use it at home, for Diptrace, i'll ignore EAGLEs stupid subscription costs, the cost isn't that high that it is unobtainable for most home users.
I have used Diptrace and while I don't actively use it, it's a good package, the developers are quick to respond to questions.
So you can't compare Diptrace / EAGLE with the likes of KiCAD as they have completely different goals.
You also have to remember that KiCAD has a lot of features that other packages lack, but when the other vendors add these features they are far more polished than KiCAD, this changes with later releases, but you still have to wait a while.
From what I can tell Diptrace still has a lot of traction for commercial use as it has one of the friendlier interfaces.
Just my opinion of course.