I have returned to using KDE, and it's wonderful! I can't remember why I switched to Ubuntu, but this is reminding me of my first years with Linux and it's terrific. (I was prompted to switch today because I couldn't for the life of me figure out how to properly remap keys and have the config stick – this bug: https://askubuntu.com/q/1284219/68491 – and everything is just so much more configurable in KDE.)
Maybe KDE isn't that great. I've swapped a bunch of non-working things for different non-working things. On balance, I think I prefer this set, but it's not all simple! Still, I've got the Wikimedia Commons picture of the day as my desktop, so that's nice.