The ultimate mice so far
>I want the lightest mouse possible
>Zaunkoenig M3K
Made out of actual carbon fiber and light as fuck, good quality, but has a mini body style 2 clicks and a wheel and nothing else which, besides the price and long wait, is the downside

>I want the most extra buittons/features possible
>Swiftpoint Z2
Has some amazing features (pic related), great design so that all the buttons are easily reachable and identified, comprehensive software (now Linux native/compatible, buit its still something of a beta on Linux). The downside is that the cord is attached and there's no wireless option yet (maybe a later revision) and its "heavy" but still lighter than most mice in the days of adding custom weights to them.

>I want a mouse that's FOSS hardware and software customizable
>Ploopy Mouse / Trackball models
3D printed body and able to be built from a kit, Ploopy's hardware is custom but also well documented. Their mouse is a pretty conventional layout with an extra button or two and the roller bearings can be loud, but if you want control of the hardware as well as the software, its worth looking into it.

>I want something ergonomic, but gaming/power use featured
>Dygma upcoming mouse project
Dygma makes some of the best gaming/power use split ergonomic keyboards like the Raise 2 and Defy, but its an open secret they're working on a similarly high end ergo mouse project. Not yet available, but keep watching