I had an iPad pro 2017 12.9, which was beautiful. Unfortunately, it died on me the other day. I think I left it in the sun too long.
What is good is having decent stereo speakers. So only the Pro has those, though the current Pro appears to have dropped in audio quality compared to the 2020 version.
But what is essential for being on the go, is having a headphone connector that allows you to charge your iPad too; those will be gone when the current “normal” ipad gets updated to USB-C.
I cannot fathom how nobody bothered to make a wireless headphone with low latency. Somehow bluetooth midi is good enough, but audio is just impossible. With any USB-C ipad you will need dongles to connect headphones, charging etc.
And another weird thing: there is (afaik) only one audio interface that lets you charge the iPad while using it: iconnectivity iconnect audio4+. Pretty cool interface, but not portable and not battery power-able.
So if you want truly mobile music, you need to get the current “normal” ipad because it has a headphone jack. The last of its kind.
If you want an M1, get the iPad Air.
If you want stereo speakers, wait for the next pro or get the 2020 one.
If you want a big display: wait, because there are rumors of a 14" low end iPad. That’s what I’m hoping for in about a month or two. That and my Osmose.