I'm on a System76 Lemur Pro these days and really love it. It's light, keyboard feels good, battery life is great. Echo the desire expressed in other comments here of wanting nicer / higher res screens. But having been on Arch+xmonad/dmenu/i3 etc. before for a while then main-ing mac since then, PopOS on this laptop feels like a good convenience combo (Bluetooth setup etc. works easily) with something like Regolith. The hardware being actually supported the way System76 does it is comforting, esp. with the open source firmware code (I don't ever do anything with that but it's just comforting in some way I guess).
I would actually explicitly pick switching from an already-satisfactory i3 setup to a Regolith setup as maybe not worth it (unless you're literally just doing it for kicks, I guess?).
In my case: I've done i3 setups before and then haven't main'd Linux in a bit, then when back on it tried to see how well I could fare with minimum system setup, and Regolith gave me a good-ish i3 config out of the box (along with dark matching GTK3 theme and terminal themes etc.). I did end up tweaking the files though to change up some keybinds and indicate fan speed + thermals in the bar. So it ended up being mostly 1) just a config starter (incl. most bar widgets you'd want) that I can also maybe rebase on if they update upstream in a way that matters 2) a way to get very consistent system theming across i3 setup and GTK.
Regolith is just a software suite like gnome-desktop that attempts to make a coherent i3 system without having to find solutions for the parts of the desktop environment that i3 doesn't manage.
Advantage of using it is you get a set of sensible defaults rather than having to put together your own.
If you're an i3 veteran there is little if any advantage to switch. I was turned off by Regoliths' key bindings which deviate from vanilla i3.Regolith does have some nice features like parsing your config to display a helpful key map.
