I’m more on the beginner side, so take my word as a grain of salt. I probably didn’t face much issues yet. My experience with blender is that it’s smooth for the most part. I did some benchmark, my 6900 xt’s score is around 2535. So basically, it’s a bit better than a 3060 in terms of rendering. But still, it renders much faster than my 5900x and HIP is fairly new, so it might be way better with optimization in the future.

The only reason I’d say choose Nvidia is bc it has way better support and most renderers like octane or a specific plugins only support Nvidia. Redshift finally added support for AMD, but right now, it’s only in beta. Either way, AMD is totally useable, but they’re nowhere as competitive with Nvidia yet. If you want to take the chance of future support, you can choose AMD. They’re slowly catching up. Tho you don’t have to worry if you choose Nvidia. You probably need a GPU with bigger ram bc 8 GBs on the 3070 won’t be enough in the long run.