There is something unmistakably naff about ergonomic mice and keyboard. Almost all people whom I had known who used them are in one of the two categories: already suffering from repeated strain injury (RSI), or wankers. The latter category is almost exclusively responsible for the naffness of ergonomic devices. You know if someone in your circle uses an ergonomic device because they will tell you, and they will laugh at you as you flail trying to use their split-layout keyboard or the scroll-ball to accomplish a task and then they won't shut up about how much better their life is since they switched.
These are the same people who will use a Dvorak layout for shits and giggles, but it is really for equal measure of "mine don't touch" effect and air of superiority and then tell you that Dvorak layout is better than qwerty and they type so much faster, but you know that really they're just an asshole, trying to be special, with their fancy, expensive, alien looking peripherals.
The rest of us won't be caught dead using an ergonomic device unless we absolutely must just so we won't be tarred with the same brush as those guys. We instinctively know it's the same thing as with wearing non-prescription glasses: I won't look down on you if you need prescription glasses, but we all know no well adjusted person every wanted to wear glasses when they didn't have to.
People who use specialised devices due to injury or disability would never think to go and recommend or lord them over others.
20/20 vision just a pair of empty frames
Dressing like a nerd although I never got the grades
I remember when the kids at school would call me names
Now we're taking over their estates
So when I started to complain about strain in my wrist and then started shopping for a new mouse I resisted with all my might from falling into the ergonomic device trap.
And now I must tell you how awesome it is. I'm that person now. Them the rules.
My new shiny mouse
My new ergonomic mouse is a Logitech because of course it is. 
They have two ranges, Lift and MX Vertical. While I don't exactly delight in products being specifically marketed to women, I have such very small hands that I had to go for the Lift. I was going to buy it for myself but my husband had beaten me to the punch and bought it for me for my birthday. Yay! New toy!
I unpacked it greedily and braced for a long adjustment process going from a standard mouse to an ergonomic one, but you know what? It didn't happen. The mouse immediately felt like an extension of my hand. The tracker wheel is exactly where I expected it to be. The side buttons are accessible yet out of the way. The weight is just right. It's just excellent. I'm completely in love.
The real trial, of course, was putting it to the test while gaming... and again, I sorta forgot I had a mouse in hand at all. Even during a long Diablo II Resurrected session I hadn't noticed any performance issues, and most importantly, I didn't feel I needed a forearm massage afterwards.
It now has been several months of using this mouse and I report the wrist strain has not returned, whether I sit in an ergonomic position at my desk or slouch like an absolute goblin shrimp.
The one complaint
The only thing that I would complain about here is the connectivity options. As a longtime Logitech user I have a drawer-full of unifying receivers. The new mouse however uses the new Bolt receiver, or alternatively Bluetooth.
Bluetooth performance was absolutely rubbish with the cursor stopping-and-jumping, a tell-tale sign of interrupted connectivity. I tried to troubleshoot the issue, but after spending an hour on it I eventually gave up - I had better things to do. Furthermore getting a Bluetooth device paired on the same PC dual-booted with Linux and Windows is not something I particularly care for: either you manually register the device with the same ID on both OSs (technically difficult and error prone task) or you have to re-pair it every time you switch (a horrid chore). I had little choice as a result to use the Bolt connector.
Bolt and Unifying receiver devices however are not cross-compatible so I couldn't connect my new mouse to the existing receiver, nor my older K520 keyboard to the Bold receiver. Result? two USB ports being hogged by input devices - not great.
At the end of the day though I must say - these mice are pricey but entirely worth it. Go get one.
1. Over a decade ago one of my Logitech mice broke, and I called their support asking if they have repair instructions. Instead they asked me if I have the original receipt or invoice (I did) and to send it into their support mailbox. Then they asked me for my mailing address and to pick a new mouse from their online store that I liked, because they are so very sorry, the one I have is no longer produced. I got a new mouse of my choice the following week. This experience made me Logitech girl for life.
I'm not affiliated with Logitech in any way and won't get any monies from hawking their products. Which is a little bit of a shame but c'est la vie.
2. Wait, how do I know it's marketed to women? Well, there are only women in their promotional video and the Lift is available in White and Pink in addition to the traditional black. MX Vertical is only available in black and has both men and women in their video, but male hands dominate. Their promo video also emphasises engineering that went into the design of the mouse, rather than ergonomics, instagram-worthy interiors, and yoga poses seen in Lift video. See for yourself:
Lift Mouse Promo Video
MX Vertical Mouse
MX Vertical Promo Video
3. My hands are 17cm long and 8cm wide. I wear gloves US size S and EU size 7. I think Lift will be also comfortable for people in US size XS or M / EU size 6 or 8, but if you have larger hands than that you'll probably want MX Vertical.