I personally use tixati, primarily because whatever special sauce they cooked it with let's it run on the trashheap of a computer I use for torrenting when nothing else I've tried does. I'm not in any private trackers, nor do I really have a need to be, and like, not being usable on Mac is entirely irrelevant to everyone not using Mac. I personally don't care if it's proprietary, but that's just down to individual preference.

I'm not really sure what feature rich means since I don't have a comparison point, but there's a lot of menus with options in them, and I figure they all do stuff someone more dedicated than myself may care about lol.