What are the best proprietary/paid apps for linux?

Reaper. Great usability and decent Linux support out of the box (looking at you, davinci resolve). Generous free trial and a cheap one-time payment for a license. LMMS has served me well and is fine for basic stuff, but reaper is a whole other level, both in features and usability. I've heard good things about ardour too but have yet to give it a try.