The cuda happy path is very polished and works reliably. The amdgpu happy path fights you a little but basically works. I think the amd libraries starting to be packaged under Linux is a big deal.
If you don't want to follow the happy path, on Nvidia you get to beg them to maybe support your use case in future. On amdgpu, you get the option to build it yourself, where almost all the pieces are open source and pliable. The driver ships in Linux. The userspace is on GitHub. It's only GPU firmware which is an opaque blob at present, and that's arguably equivalent to not being able to easily modify the silicon.
If you don't want to follow the happy path, on Nvidia you get to beg them to maybe support your use case in future. On amdgpu, you get the option to build it yourself, where almost all the pieces are open source and pliable. The driver ships in Linux. The userspace is on GitHub. It's only GPU firmware which is an opaque blob at present, and that's arguably equivalent to not being able to easily modify the silicon.