I’m extremely wary of Manjaro in general. I don’t personally care for their approach to package management (delaying the Arch core repository but still relying heavily on AUR seems like a recipe for instability to me), and the Manjaro team have shown themselves to be less than reliable.
All that said, if you’re mostly happy with Manjaro, then Arch or Endeavor might be the way to go. They use the AUR (Arch of course is where the AUR started, and Endeavor is based on Arch, but doesn’t delay or muck with the Arch repositories the way Manjaro does).
Endeavor is super easy to install. Cinnamon is one of the available DEs on the installer image, and their system tools are good. They also have an active community and haven’t (to my knowledge) accidentally DDoSed the AUR with an update, so they seem more competent than the Manjaro team.
Arch, of course, is the forerunner to Manjaro. It’s slightly more difficult to install than Endeavor, using either the archinstall script or the Arch Method, but kind of worth it for the level of control it gives you over your system. Since you make your own post install scripts, I don’t think you’d have much issue here. Cinnamon is (of course) available, and the community is extremely knowledgeable, although they do expect you to be able to RTFM and perform basic troubleshooting on your own. As an added bonus, you get to say “I use Arch BTW” with a sense of either irony or smug superiority. Both are good.
I use Fedora, BTW. It has Rawhide for bleeding edge, Copr for expanded packages, and a Cinnamon spin. I don’t think it’s a good match fr what you’re looking for, but it might be worth looking at.
An up side to all three of these is that you usually don’t need to reinstall your whole system multiple times a year to keep it clean and running smooth. That was my experience with Manjaro back in 2016 or so, though, so I can see why you do it.