I use both niri and i3wm.

Here is my take: i3wm is amazing. It’s my preferred wm for keyboard and mouse workflow and professional work. Everything just works, your mind is clear, you have tabs which is literally the same concept as niri but cleaner. And you can structure your workspace very efficiently.

Niri is also great, my main problem is with wayland itself. I don’t care what anyone says, all my things work much more simple and with less effort under X11 and the fragmentation of wayland ecosystem drives me nuts. I’m not a fan of hacking your way into every single thing you want to do and exploring a plethora of docs for everything. But lets forget about this.

Niri itself is amazing for a laptop touchpad workflow. It is so efficient, enjoyable and cool when you have a touchpad. But it’s not as organized and efficient for serious work with many windows as i3wm. But for light work it’s just delightful.