Here at work, I've gone through a few different mice over the years. The most recent rodent of choice is the Razer Imperator. I absolutely love everything about the mouse. The ergonomics fit my hand perfectly. The scroll wheel is perfect. The braided cord never snags.
There is only 1 simple, but work-halting problem: double-clicks right now have about a 50% change of going through, which leads me to believe the switches are finally giving up the ghost.
In an ideal world, I would just buy another one. However they stopped making them. I tried a $25 Logitech M500 which looked to the the closest dimensionally, but it just doesn't fit my hand right. The lack of a "clicky" scroll wheel is also a dealbreaker. I don't mind spending the $$ on the right mouse, I just can't afford to keep buying the premium one's until I find what fits. Maybe I just need to go by the Best Buy and see what fits. The closest current Razer might be the Naga Trinity (with the 2-button sideplate).
Has anyone else moved from the Imperator to a different mouse? I don't really need anything like high-DPI sensor or more than 5 buttons or RGB, but they don't bother me if that's what it takes to get the ergonomics.
EDIT: spelling is hard.