I would argue that Nouveau is bad purely because of poor performance, and the proprietary drivers are tolerable but perform well once you have them working.

One thing I can say for Nouveau over the proprietary drivers is that they actually work without any real fuss. I've run into numerous instances where the proprietary drivers would prevent the system from booting. And I've yet to get them to work at all with any realtime kernel in Manjaro.

And then we get into the nightmare that is any laptop with an integrated Intel GPU and a dedicated Nvidia GPU...