Yeah, I never really got why they bothered with KDE. The great thing about Mint is Cinnamon (and Mate to a lesser degree). It's meant to be a clean, stable, customized OS... but that also means it's using older packages from Ubuntu. KDE tends to be more cutting edge (sometimes bleeding edge), and I don't know that the KDE version was as well polished or customized as the Cinnamon one.
I tried to stay with Mint, but at one point, I needed a kernel it didn't offer for a feature I wanted... and then I couldn't get a newer version of VLC because the repositories had a much older one. Same for several other programs. Eventually, my system became unstable from all the modifications, so I just wiped it and went with Ubuntu with the Cinnamon DE.
Mint already has too many flavors imho -- and ones based off of ubuntu and directly off of debian as well. It's a small team, and I'd love it if they'd just focus on the Cinnamon DE and make an official Cinnamon flavor of Ubuntu (with Wayland support, too!). But, I understand they have different goals. I just think they bit off more than they can chew with all these flavors.... especially with KDE.