GPU recommendations?

So I'm considering upgrading my current setup from a 5820K to 9700K. And if I'm gonna spend around $1000 - $1300 for a new CPU, mobo, RAM and a M2 SSD I might as well throw in a AMD GPU.

The sad part about it is that I already have a GTX 1080 Ti so I feel reluctant towards buying a second GPU only for dual booting to OSX. The thing is I work as a iOS developer so I need to be able to run the latest OS's that is Success' href='/2020/12/install-macos-mojave-on-supported-pc.html'>Mojave and Success' href='/2020/12/install-macos-catalina-on-supported-pc.html'>Catalina.

What are you guys' recommendations here? Apple will probably never let Nvidia back into the eco system right? Should I go for a cheaper Radeon RX 580 for around $259 in my country or is it really worth it to spend somewhere between $419 - $589 for a Radeon RX 5700 or a Radeon RX 5700XT that's still considerably worse in performance in comparison to my GTX 1080 Ti?

Author: @andyscorner