AMD: some open source drivers, but many things are inop
Nvidia: all closed source, but everything works
Source: I have a Vega 56 and I am gonna give it the sledgehammer when 3000 series arrives. Fuck that shit to high heavens my dude. ROCm is buggy as fuck. Only the bare basics work on Linux. Drivers are buggy, and crash all the time. Even the most basic bullshit is not implemented right. Like there is no fan control. That's how bad it is.
I thought AMD had great Linux driver support, and open source drivers.
Turns out AMD only has the open source driver part of the things, and this driver does not support a large chunk of their products.
I'd take a binary driver over no driver any day (and in fact, I returned the amd card and am using intel now, which works great).