Roccat user because of the size of the mouse is bigger than others and all the buttons can be reprogrammed, along with the wheel. No background software needed and all configuration changes are OS independent.
Not a Logitech user because the wheel could not be programmed to control the sound volume. Last time I tried their products. Even contacted their support to verify the wheel, most useful for controlling audio, is fixed to page scrolling only.
Razer mice are too small for my hands and I feel like an Eagle clawing at a minnow. At least they allow for fully reprogramming all the buttons and wheel, unlike Logitech. And you don't need background software for the programming with it being OS independent after programming.
Only bad part is that Roccat is no longer Linux supported. The original developer that reverse engineered stop supporting the products. Roccat also is like most business and blows off 1st party support for Linux. Windows VM is needed just to program the mouse, which only done once.