Been using Plasma 6 in Arch for a bit now and I have to say I’m very impressed. The 6 branch has fixed a variety of annoying little quirks that bothered me about KDE. It feels very good to use.

LMDE essentially is Debian (uses the Debian repos for most of its installed packages), with some Mint packages included on top via the Mint repositories that are also added. Mint actually has some pretty neat graphical utilities and has Flathub configured to work by default with the Software Center.

The real benefit though is if you enjoy using the Cinnamon DE. The latest Cinnamon version is kept up-to-date in LMDE as the Mint team backport it. The Cinnamon version in Debian 12 is fixed and will not get major version updates until the next version of Debian.

As a Debian user myself, I enjoy Mint when I wish to use Debian on the desktop. I only use core Debian for servers.