Here's a newer script that overall seems to work better: https://github.com/lingtjien/Grid-Tiling-Kwin
And the older script I used to use: https://github.com/faho/kwin-tiling
I still have my treasured xmonad config available as an xsession for when i'm just doing dev things, and use it most of the time on the laptop I do programming with, but in general plasma5 is such a step up from any older versions of KDE it just works really nicely for everything else.
I'll have a look at the KDE tiling plugins although I'll be surprised if it can replace my xmonad setup (would be nice though).
There are a very few things that I will drop into Gnome to do (I think it's Gnome at least), and I dread it every time. Too many menus everywhere, too much animation, tiny targets that I need to hit with the mouse, etc.