Not having used every equalizer on the planet, I am not in a position to guess which one's the very absolute bestest of the best. But among those that I have used and learned well, FabFilter's Pro-Q is easily the best, and by a wide margin.
The best feature of Pro-Q is the ergonomic way you can configure M/S processing. Although I'd had the ability to do M/S EQ since Ozone 4 it seemed like kind of a semi-useless gimmick. But Pro-Q made it easier and more intuitive, and once I got the zen of M/S EQ it was a revelation, and totally changed the way I apply EQ.
Pro-Q goes on almost every track and bus, although admittedly I could probably use just about any equalizer for that. It's as a mastering EQ where Pro-Q really shines.
I have no idea why anyone would say it sounds "harsh". I have never heard any harshness (although it's the kind of nonspecific adjective I'd normally avoid anyway). I can drive it as hard as I want and there is no distortion. I have tested it for aliasing or other frequency distortion and found none. I have compared it to other equalizers and it performs exactly as expected, even at the highest frequencies. If there is some kind of distortion happening in there it's neither audible to me nor measurable by any tools that I have.