New CPU - Intel or AMD?

[Lyris]

I'm a little confused on what to buy, because most of the CPU reviews online, for obvious reasons, only give an idea of encode speed with x265 for RE-transcoding already compressed video.

For first-gen encodes from an uncompressed YUV source, the speeds are of course much slower. I'm running a bunch of AMD Threadripper 1950Xs and also one 2990WX. The typical speed for encoding content with film grain on the veryslow preset is about 0.19fps (although on the 32-core 2990WX we can run two chunks concurrently and get about 0.15fps on each).

Supposedly, whatever design issue the 2990WX had which stopped it getting better performance gains has been solved with the new chips, and I'm told that one of the newer, beefier Threadripper CPUs would hopefully show some performance gains.

Or, should I only be looking at Intel - maybe a 10980XE - so we can benefit from the AVX512 extensions? Is anyone else out there running high end CPUs for 4K content encoding, and what sort of speeds are you getting with film sources?