I use the mouse a lot when I'm on a PC. And I have very specific expectations to a good mouse that I haven't seen met in any product. I know that my expectations must be high, considering that others don't seem to have them. But I also think that the differences between a 20 Euro mouse and a 150 Euro mouse are very small. I believe that others would like a mouse with the features that I desire in a good computer mouse. They may not realise it because it doesn't exist. But I would be surprised if I woudl be alone with these preferences. I'd like to describe those features here for that reason, but also with a little bit of hope that somebody might have a tip for me for a product to try out.
Form Factor
Most ergonomic mice are restricting because they prevent switching the position of the hand from time to time. Therefore I'd profer a simple shape with no unnecessary folds and pertrusions. There are some not so default mouse designs though that I don't mind, like those that hold the hand in a 90 degree rotated position, as if you're going to shake somebody's hand. That form factor likely prevents issues with your wrist. I'm not considering non-mouse pointing devices, like joysticks or trackballs. Althought I like the idea of a pointing device that only sends out positional information relative to a screen's center and physically snap back to their center position when untouched. I'd try one of those if it would be supported by an OS that I'm using.
Buttons
I don't really need more than three button. with less than three, I definitely miss the missing ones. But I never got used to additional buttons enough that I'd use them regularly. The same goes for additional wheels. Three keys and one wheel are enough to to many things on its own. For more there are enough additional keys on the keyboard to press and hold down. So I'd prefer there to not be any additional buttons that could be pressed accidently and cause unexpected/unintended behaviour. The three usual buttons should be hard to press compared to most mice. I would like to have to use some force so that it is impossible for me to ever accidently press one by sliding across the surface with a finger, by slipping off the scroll wheel or from random finger spasms. I don't need to be able to click repeadedly very quickly. I don't want the buttons to bounce back to support additional clicks. I want an anti-gamer mouse in this regard. Touch fields that aren't disabled by default also are unacceptable to me. I don't think I'd mind a bit of travel as long as there is a clear clicking point.
Caseing, Size and Weight
I wouldn't mind a rugged case that doesn't mind being handled roughly. Or a sealed one that doesn't mind being under water and can be cleaned easily. A metal case isn't so nice because it can feel uncomfortably cold. But metal parts would be good because they add weight. I haven't had a mouse yet that's as heavy as I would deem ideal, even after adding steel weights. But most mice can be brought to a comfortable weight by filling most of their free space inside with steel parts. The other things where I'd like my ideal mouse to go above what's considered reasonable is its size. I don't want my hand to hover over the mouse like a spide with long legs. I want my hand to completely lay on the mouse. The wrist on its back, leaving the forearm lifted from the table; the fingers resting on their respective buttons without bending up much. My hands are surely larger than average (although I've seen people with much larger hands.) So a mouse for me should also be that large. Some ergonomic office mice come close to such a comfortanle hand position. But they seem to be made for average-sized hands. I haven't seen a really large mouse like that yet. Maybe what I feel that I want would look rediculous. Maybe it would be so. But so did 5 inch phones when they first came out. And I argue they also fill hands more comfortably.
Scroll Wheel
I have very specific ideas of how the scroll wheel of the perfect computer mouse should be. There should be exactly one. I should be between the left and the right button (because that's what I'm used to and it works very well that way, not because I believe there have been enough expreriments for the perfect position), pertrude above the left and the right button about 3 or 4 millimeters and be about two cenrtimeters in diameter (or a bit smaller). It should serve as the middle/third mouse button. (That one isn't necessary, but very useful sometimes.) So far so usual. It should not be tiltable to use it for additional buttons/functions unless this feature is deactivated by default. The wheel should have haptically clear steps or clicks that reliably corrospond to scroll steps. It should never come to rest between two steps. Some force should be necessary to turn the wheel so what brushing it on one side accidentally (as an example) won't turn it a click in either direction. The surface of the wheel should have a rough and deep rubber profile. Only very few gamer mice ever had scroll wheels with a profile as rough as I want one. And of those most have been changed for mass profuction. And of the one remaining mouse with a scroll wheel nearly as rough as I would deem minimal, only the first shipment had it. Even in mice with changable wheels or surfaces I've never seen one with a grip nearly good enough to call it acceptable. Basically, what I want it a scroll wheel that never turns unintentionally, always turns 100% reliably when turned intentionally, even with greacy as fuck fingers because I'm eating chicken wings in between very important scrolling action and I don't have time to wipe my fingers. There should be little rubber spikes or canyons that aren't reduced to a millimeter after a few years of scrolling (or the wheel needs to be replacable).
Battery, Wireless, Cable
Of course a wireless mouse is nicer than a wired one. Battery powered devices should have standardised replacable batteries. But I see the problems with that in mice. Nowadays I would actually be OK with a non-replacable battery in a mouse (I am already). But I'd also like one that takes Canon LP-E6 batteries or similar small camera batteries. If it is a wireless mouse it should use little currents to make it work. With a battery with 1.5 Ah or more charging shouldn't be necessary more than once a year. But a wired mouse is OK, too, if it has a good silicone cable.
I may be like Homer Simpsen when he designed his dream car here. But I expect that I will only be convinced of that by giving me my supposed dream mouse to use.