Do not buy anything now. New ryzens coming out very soon.
When these due? Doubt we will see early than Nov/Dec, recently we have XT Zen2 updates.
If OP cannot wait, perhaps save money on CPU now, and spend $$$ on a proper MB and memory that gives confidence in upcoming Zen3 CPUs later.
https://www.amd.com/en/chipsets/x570
Also, SSD must if HDD still in a place.
As per OP's software list, I think Vegas Pro and some Adobe will utilise many cores, everything else still depends on a single-thread...
So, cheaper 3600X(T) beats to the dust i7-5820K with significant performance improvement.
My board budget is about $300. I was looking at the ASUS ROG Strix X570-E, but I'm open to suggestions if somebody knows of a nicer X570 board around that price (or so). If I go the Intel route, it will likely be with the GIGABYTE Z490 VISION D, which I prefer over the ASUS specs, and much prefer the Gigabyte i/o panel.
My system drive is a 970 Pro M2 SSD drive. My audio drive is a 850 Pro SSD. I also have about 10 more TBs in a SSHD and HDD for other storage needs. I'll be okay.
I like the idea of using the same board with the next gen chip, which will be an option with either brand of processor. Intel's next gen chip will (allegedly) support PCIe 4.0 and still use LGA 1200 sockets. I don't care about video cards, this also affects SSD drives in M2 slots (for example). Whether I go with a Z490 board, or a X570 board, it doesn't really matter. Even if both brands next release works on these boards, they will also be releasing newer chipsets with whatever improvements come with them. Both brands are likely to release new chips in Q4 2020, or Q1 2021. I don't need the lastest chip, it's obviously been a while considering my 5th gen "enthusiast"
chip still performs well.
Thanks,
Josh