[Obsidian Dragon]

I think the maximum benefit would be achieved by maxing the RAM to 32GB. This is mostly because the i9 processor is already a beast. Of course, this depends on your workflow, the number of tracks, and how you use VI's and plugins.

Next, I would look to bump up the processor. Protools has always been processor hungry so the more processing power you have the better. The speed bump is only marginal but every little bit helps in Protools. Once again it depends on your workflow, the number of tracks, and how you use VI's and plugins.

So you got the two top options correct.

As for the GPU, neither will offer much of a performance improvement for Protools, but if you are driving multiple monitors via USB-C/Thunderbolt to Display Port at high resolutions and refresh rates, the better GPU will run more effortlessly. I doubt you will notice much a difference, however.

One final word. The SSD in the MPB is not replaceable so get the size you need. You can use external Thunderbolt drives but that internal PCI-E SSD is blazing fast. For most projects, it can handle the full load.