Depends on the use case, as for hardware h265 codecs a rtx 5070 Ti works just as well as the rtx 6000 gpu. Legacy GPU don't support modern codecs, but modern Intel chips have h265 HDR hardware support. Lower <16GB VRAM GPU are not really useful for "AI" model labs, so are often far more economical for rendering media.

https://www.pugetsystems.com/pugetbench/creators/davinci-res...

https://www.pugetsystems.com/pugetbench/creators/premiere-pr...

In some cases it is better to have lower passmark scores:

https://www.videocardbenchmark.net/gpu.php?gpu=RTX+PRO+6000+...

Blender is heavily bottle-necked by ray-tracing and de-noising operations:

https://opendata.blender.org/benchmarks/query/?compute_type=...

One metric that isn't considered is VRAM, as some rendering pipelines still rely on composited baked-scenes to reduce each areas memory requirements.

In general, the $/performance unit will depend on what you are doing, but there is 1 more thing to consider... Old GPU use mystery binary BLOB drivers no longer maintained on modern kernels. You might get the software to work with a legacy Windows GPU driver, but the key takeaway concept here is "might". =3

Benchmarking 15 "E-Waste" GPUs with Modern Workloads