Also, how exactly do you choose a default bootloader when each distro automatically installs their own?
I’d probably let Debian or LMDE do it simply because I’m more used to those distros, but you can simply roll a die if you want.
Or, if you already chose which distro should manage boot, and you want to know how to do it - the tutorial in the link does the trick. I’ll adapt and copypaste a simplified version here:
how to let the distro of your choice manage boot1. Install all distros the way that you want. Make sure that you know in which partition each is installed. 2. Pick the distro of your choice to manage boot. Let’s say that it’s Foobar Linux, and it’s installed in /dev/sda69. (why 69? Because it’s funny, so you’ll remember to replace it with the right number later on.) 3. Boot in some live USB. The distro in that USB doesn’t matter. 4. Open a terminal. Type the following junk in it: sudo sudo mount /dev/sda69 /mnt for i in /sys /proc /run /dev; do sudo mount --rbind “$i” “/mnt$i”; done sudo chroot /mnt update-grub 5. This should be enough. Now restart your computer without the live USB, and your Foobar Linux should be managing the boot.
And just now I realised that some random distro might decide to take over the boot, once it updates kernel (as it triggers updating grub). So when installing the other distros, look for some configuration that allows you to not install grub in it. (It’s also possible to remove it after the installation of the distro.)
Or do things like display managers matter? or is Xorg or Wayland pretty much good for all three?
That’s a per-distro choice, you could go with Wayland for some and Xorg for others. I would probably go with Xorg for all three because it works for me.