Even non-productivity too! I'm a gamer and I find games to be more "fuller" in 16:10, if that makes sense. I mostly play RTSes and A/RPGs, and recently switched from a 32:9 ultrawide to a 16:10 and I find it better, at least for the games I play.
You can pry my 49" 32:9 monitor from my cold dead hands.
Seriously though glad you found something that works for you. I could see them being difficult for RTS/ARPGs. I've started getting back into racing games because of my 32:9 because being able to use the side mirrors is cool as hell.
I would prefer 2x 21:9 over 3x 16:9
With proper use of window snapping it is superior for research.
But for general productivity I see personally no real upside between 16:9 vs 16:10. Our office administration recently complained it's too constricting so....Some are fans.