Your old PC is about the same as mine currently, I've been thinking about upgrades too as my pcis started to struggle to keep up with my streaming setup, generally running out of cpu though there are config changes I can make to aliviate the problem.
I'd go full AMD as I wouldn't buy nvidia purely because I'm an AMD fanboi lol.
Price is a big factor preventing me from upgrading atm. I think I could manage until the next release cycle.
At least now you could probably not upgrade for 3-5 years unless there is some crazy breakthrough or ultra fancy feature to get.