After years of using Gnome 3/4 with a modified setup on Debian, I returned to Xfce, and am quite impressed by the state of Xfce 4.18.
My background: Using Linux since 1998 or so (yes, I am old) as my main OS, I used a lot of different window mangers and DEs.
Gnome 3 actually never really matched my personal workflows, but I always discovered many paper cuts using other desktop environments and thanks to dconf at least I could automatically configure Gnome 3 in a way which made it usable for me.
For life reasons I needed a cheap, small sub notebook (or netbook, as it was called when I was younger), and settled on the HP Stream 11 with an N4120. No way to run Gnome on this machine and work fluently, so I recalled that Xfce was at the sweet spot between being full featured, fast and light on memory. (+stable and Gtk+ based, KDE hasn't been an option for me since 3.5 and I check it regularly.)
I got more than I bargained for, Xfce felt so quick, responsive, good and simply sane that I run it now on every Linux desktop/laptop I own. (But my entertainment system, which I only use for Netflix.)
What I really like about Xfce 4.18:
- Speed and responsiveness, even on my beefy machine I feel the difference
- Sane size of titlebars etc.
- Customizable panels out of the box and xfce4-panel-profiles for 1 click setups
- Thunars split view. I get tired by the Gnome developers, who removed this feature from Nautilus, explain that two Nautilus windows side by side are equivalent to a split view. It is not
- Ansible support for xfconf out of the box to automate the deployment of my configuration
- Light on RAM: Around 400 MB vs a little above 1 G for Gnome
- Everything I need for my DE is included, no search for plugins which might or might not fix my problems
- Useful and fast default applications (Thunar, Mousepad, Parole...)
- After tweaking the hotkeys/shortcuts a little bit a perfect keyboard driven experience
So far the only 'downsides' I have with Xfce 4.18 is the lack of Wayland support (AFAIK coming with 4.20), the Terminal does not resize the text area if you add new tabs (easily fixed by configuring it to always show the tab bar in the terminalrc) and the type-ahead launchers (whisker-menu, xfce4-appfinder) are 'weaker' than the type-ahead launchers in Gnome/KDE.
Big shout out to the Xfce developers for this excellent desktop environment!
tl;dr: If you haven't used Xfce for some time, give Xfce 4.18 or later a try, you might like it.
To try i3 'for real' is on my someday list.
Just a question: Isn't there an option to replace xfwm with another window manager (=i3)? Did you consider this option?
It's a real pity the applications for Gnome break the style/usability patterns with their hamburger menus... It's especially annoying because it means more clicks on our side.
Don't know too much about the Qt world, KeepassXC/Calibre are the only Qt apps I use, and they work excellent with every DE/WM.
I did try it, but it either did not work or it broke something. It was definitely something on my end, because it should be possible to do this. It was quite a few years ago, so I do not remember many details. Sorry!