I’d suggets Void. It has Ardour in the repo (not Reaper though) and PiperWire with JACK should work out of the box. If you want Reaper, you’d have to install it manually though. I’m working on a template for Reaper, but it’s not finished yet. If you’re willing to wait a month or so, you’ll probably have Reaper in xbps-src as well.
Do you know any other distro that’s not LFS or Gentoo that still supports x86? I said a lot, not everything. Most distros don’t support anything below 64-bits.
A fork supported PPC up until a while ago. That project halted though. There was a new spin on it, can’t remember the distro’s name though.
xbps-src can cross compile for MIPS. There are no packages in the repo for MIPS though.
No, it’s not Arch without systemd. Arch breaks a lot more than Void does. Ask Void users when was the last time a Void update broke their system. I use it as a daily driver, plus for a lot of other things (at work and home) that are considered mission critical. I would never use Arch for that. Also, it’s faster than Arch, it supports A LOT more architectures than Arch does… or any other Linux distro for that matter (LFS excluded).
The repo is full of any software you might need, including proprietary (through xbps-src).
Everything just works, if it doesn’t it’s probably your fault.
It’s a rolling release distro, yet focused on stability and usabilty, so you won’t get the latest and greates, but instead builds that are known to be solid. For example the kernel, it’s not the latest, as is with Arch, but it’s maybe one or two minor versions behin. The same applies to software, they’re known to jump versions if the current build proves to be unstable.
Lightning fast boot up. It’s also the fastest distro there is, apart from the *BSDs.
Compiling and testing is a breeze thanks to xbps-src.
A lot of tools and scripts that make building templates for software not in the repo very easy.
Supports a lot of architectures. NetBSD is the only other POSIX OS that supports more architectures than Void.
There are other things, I’m sure, but these are the ones I can think of ATM.