You really should give KDE another go. KDE5/Plasma is the most coherent UI available on Linux, by a long way.
KDE Neon is a KDE-focused distribution, using Ubuntu LTS as its base, with a pleasingly minimal default install. Every Ubuntu PPA I've tried works just like on base Ubuntu. Similar to Linux Mint and others, it works as a live distro so you can check it out before you commit.
KDE4 made me switch away too (I chose Linux Mint), it simply felt too much like a transitional release cycle. KDE5 brought me back, big time.
I gave a try to KDE at the beginning of 2014. I used it for a few months but everything was painful: twice as many clicks to get things done than I used to in Gnome. It reminded me of Windows.
I installed Gnome Flashback and stayed there. I'm customizing Gnome Shell to look like the old Gnome 2 now. I have to sort out a couple of problems with the Nvidia driver (flickering unless I use a strange 40 Hz refresh rate) and I'll be there for the next few years on Ubuntu 18.04 LTS. If there won't be themes anymore by then, I'll switch to something else because the Gnome developers and I have two really different ideas of the desktop. Ironically I'm closer to KDE but it was really unusable.