XFCE is super modular. You can turn off individual components. You can enable any program to start with the XFCE session.

So, for example, disable xfdesktop and xfwm; enable other window manager of your choice. Then, when you run xfce4-session via any mechanism you get all of XFCE, but with another window manager. You can pull up xfce4-settings manager to handle all system settings as you would in any other XFCE session.

I am pretty sure that LXDE/LXQT allows this sort of modularity as well. I have no clue about KDE and Gnome.

Of particular note, you can combine XFCE's panel applet with a tiling window manager. So then you can keep an application menu and notification area (with associated notification settings) from XFCE with an arbitrary window manager.