I’ve been using the wired 3M vertical mouse for about 15 years now
With the large base I can rest the side of my hand on, the grip is more relaxed than any other vertical mouse I tried. It’s not very popular because it’s expensive and there’s no mousewheel – I’ve compensated for the latter by learning to use middle-click hold scrolling in web browsers and remapping scrolllock/printscreen to mousewheel up/down.