When my old mouse died, I bought a vertical mouse and sold it after a week. I was just too cumbersome to use. When I use a mouse, I keep the forearm and the wrist static and move it mainly with the tips of my thumb and pinkie. This was impossible with a vertical mouse, which expects you to grab it with the whole hand.

I found a regular mouse instead, but a decidedly asymmetrical one. This way my hand can stay in a less pronated position while still controlling the mouse the way I am used to.