MX Master replacement

[Andythe Random]

I have been using the Logitech MX Master for a while now, it is great quality, but has never been completely comfortable.
My hand is relatively small and unless I hold it quite well back the ridge on the top left presses into the tendon between my thumb and first finger.
Any suggestions for something of similar build quality, but more rounded, maybe a little smaller?

 

[Andythe Random]

I am not tied to logitech, I would like something of a similarly sturdy build quality but a little smaller and rounder, wireless and with at least a few customisable buttons.