no link --
I just upgraded my 2013 iMac to a 2019 5k Retina iMac. A bit more than $3000, but not much. Mostly seamless, but I am running latest macOS and tools. I use Logic, so PC is not in the cards.
If you are a Studio One, ProTools, or other DAW user, then not a problem.
The "cost-effectiveness" shouldn't be measured against the computer you choose, it should be measured by everything that you do surrounding your music production business. All the tools that you use. All the gear that you connect. All the "other" things you do as part of the workflow.
ProTools and gear? Dedicated studio computer? Sure, a PC will probably get you faster performance at a possibly lower price. Studio One? Same answer.
All around, do everything else as well as the music? I'm a Mac person with too many years of in-bred workflow. If I switched to Studio One and a PC I would be 5 years behind and have to re-train.
just my opinion.