At this point I know of two Ubuntu features that would make a difference to end users: PPA support, and the Device Manager.
PPAs are/were Ubuntu's answer to the question "What if the software I want isn't in the repository?" "Well the vendor will host a personal package archive, you can just add it and then still use APT." From where I'm sitting, Flatpak and/or Appimage have completely invalidated any use case for PPAs, I haven't installed a package from a PPA in years.
The Device Manager is handy if you have an Nvidia GPU, open Device Manager and click the one that says "Recommended." IIRC this is an Ubuntu-derived feature not available in LMDE and as soon as I own an AMD GPU I'd have less reason to not use Debian Edition.