Last time I used kubuntu ~5-6 years ago and it was pretty buggy. Has that improved? I'm on pop os and would probably just apt install to try it out. Is the kde version on pop os lts buggy?
I'm on KDE for the last 2-3 years on multiple machines, and I can't say I spotted any KDE bugs. My system is debian testing + KDE though (and I tried it on Manjaro as well). Sometimes it's not the DE, but the distro they come in. Kubuntu reviews bemoaned regressions, for example - some kubuntus worked well, and the next ones didn't.