That's a great processor and nice GPU. You've built a nice performing system... although your 32GB is limiting your potential in editing, bumping that up to 64GB would be noticeable.I guess it depends how old, and how expensive the Mac Pro is (they're hella expensive.)
My system is an AMD Ryzen 3900X, Nvidia 2080 Super, 32GB high-spec RAM, etc. edit: It's one of the fastest video rendering system I've seen, other than seeing people with the latest Mac Pro stuff. This is stronger than my dual-CPU 24-core Xeon 192GB RAM setup that's aging a bit, but I have a feeling it has a lot to do with lack of proper GPU on the Xeon.
Also, I wasn't dogging the Mac hardware -- I was just asking what specific benefits were seen by moving from PC to Mac, other than software options. If that's the case, then so be it. Software preference is obviously VERY important.
It's a nice new processor and it's 12 core does very well... and yes on many tasks, will outperform 24 cores. Other tasks, the 24 would be well utilized. The RTX 2080 Super 8GB is a great GPU, focused primarily towards gaming and vector graphics... and video editing would be well served.
No "dog" issues, was just expressing the benefits of a Mac side build up that avoids the typical $10-20k Mac cost for comparible to an older build-up. Windows hardware will be lower... I was focused on the Mac side with inquiring questions on benefits.
In comparison, the 2080 provides
3072 CUDA cores with 8GB, the 1080Ti provides 3584 CUDA cores with 11GB.
For video, the faster speed of the 2080 and higher GB of the 1080 provides close to the same video performance... edge goes to the newer GPU most likely. In 2D Ortho and 3D modeling, the 500 additional CUDA would provide additional processing... depends on the task at hand.
Overall, comproable systems on whole.
The FCP Editor may have an edge in some opinions, has a different methodology in processing and workflow that many perfer, but that's more preference in some respects.
In my opinion working on multiple platforms daily, I simply perfer the Unix architecture the Mac OS provides. Not just for memory operations or differences in file structure, the flexibly in the OS system and lack of license or activation issues is a benefit. Prior to Windows 10 64bit architecture, the Mac's architecture provided more benefits for large programs. Plus, I prefer running Mac products and Windows products and that's only possible with Macs.
The Mac side does come generally at a higher cost and Windows boxes are more common and availability for components. A minor self-justification when able to build up a Mac at a reasonable cost.
Systems as in your build or a revamped Mac Pro provide strong video editing... it sounds like similar total component costs too.