Nvidia is not nearly has bad on Linux as people say and Radeon isn’t nearly as great as people say.
For your usecase I would 100% go with an Nvidia GPU. It will work so much better with Blender. It will also work better with other workstation tasks like video encoding and AI/ML. AMD’s open source driver doesn’t support the AMF encoder, so you’d have to use their proprietary driver (and lose the benefits of the open source one that everyone raves about) and ROCm is improving, but it’s so far behind CUDA it will end up holding you back for AI/ML compute tasks.