My brain says get a 3900X and a high end X570 board and benefit from the insane MT capabilities. ST performance is shy of the current 9900K, however, it has 4 more cores and associated threads. My heart tells me wait for a 10 core 20 thread Comet Lake processor on 14nm which may very well perform better than the 3900X, if at a higher cost and more heat output. However, it'll be headache and debugging free for me. I'd really love to go back to AMD after having not used them for close to 20 years but the reality is it seems you still need to configure and pick out parts to avoid problems down the line. I was hoping AMD had gotten past that hump and didn't have troublesome launches.
Unless y'all can recommend a way to extend more life out of a 4th gen IvyE workstation processor.