mac pro 2013

For many reasons i would choose the Mac Pro but in a few months it will be 8 years old and probably have only two maybe three years left before both MacOS and Logic will no longer be upgradeable. (checking) In fact Big Sur will only run on an a late 2013Mac Pro, so the 2013 Mac Pro is at or near the end-of-life scenario for MacOS upgrades. I can pretty much guarantee Big Sur will run slow on the 2013 Mac Pro if it will run it at all. You dont have a lot of time before the Mac Pro wii be left behind.

Don't know about the minis, but you have a more time to remain current.

I would go for Mac Pro as you have more opportunities to upgrade RAM and Storage also more cores more possibility to work with VST's.

More ports on Mac Pro, you can built nice system around it including rack mount.

It's MacPro all the way!

It all depends what do you work with, if you need regular updates from logic or macOS Pancenter might be right but it's all speculation as well. 5,1 was supported for years and there is only one MacPro model after 6,1 so i don't think so they would cut it out as you still can buy them in Apple store along side new 7,1. On those basis i think it will be supported for much longer.

Yes 2013 does have rack mount as well. https://www.sonnettech.com/product/rackmacpro.html

It won't, 2013 MacPro is already on the list of supported devices.