I've been on I3 with nixOS (and emacs as my go to editor) for a few years now, and it's a dream. I can carry my configurations between machines with almost no setup. Every computer I use is the same.
I find Windows and macOS painful to use. Constantly hunting around for applications I have open, that requires me to remove my fingers from my keyboard and play around with my mouse. I barely bother to use tabs for anything (terminal or browser), just switch to another workspace and pop up another instance of FireFox or a terminal.
TWM do ruin you though. Once you're comfortable in them, you'll never want to go back and so using somebody else's computer just feels alien.
Ooh, another NixOS user! I'm curious about your setup;
Do you use the same NixOS configuration across machines?
Do you use i3 with another desktop environment or by itself?
Same configuration across different machines (apart from hardware.nix). I have a configuration.nix, networking.nix and packages.nix that pretty much covers everything. Then there's my .emacs, bashrc and my i3/config files. There's probably a way to get those last three into my NixOS config, but I haven't really investigated that.
I only use i3. Haven't found a reason to install another WM yet. I tend to use xrandr, pavucontrol and wpa_supplicant quite happily for most of the stuff people use a GUI WM for.
There is, it’s called home-manager [1] and it’s a pretty nice way to manage your config files and user packages even if you’re not on a NixOS system.