Ive been making blender porn for half a year. Nvidia for rendering. 100%. Most rendering software uses cuda, which is what nvidia is. Amd uses hip/rocm, some software also use it but its usually a lot slower. A 7900xtx and 4090 for example. 7900xtx trades blows with the 4090 in games when it comes to rasterization. But 7900xtx is like 1,000usd cheaper. In ray tracing, 4090 pulls ahead. When rendering in blender (you can look it up, i think pudget site?), 4090 is like 3x faster than a 7900xtx. So if you render a 1minute animation that is 30fps/1080p (1800 total frames) and its 3minutes a frame with the 7900xtx you will save yourself tens of hours on rendering time.

Also.. more vram the better. AMD gives more for cheaper price but at expense of slower rendering. 16gb is barely enough. 24gb woypd be ideal for larger scenes or scenes with more than 3 high quality models.

I got a 4080 last year. Its a mistake because of vram capacity and shitty price.. but my gtx 1080 was not cutting it last year and 4090s kept selling out. Ill probably get a 2 computers, 4090 (to render) and a 5090 (to play games or work on next animation while 4090 renders), next year. Will sell my 4080 probably. But still trying to make enough money for that investment.