Very much mean the physical config. I have NFL Lineman sized hands. Most commercial mice make my hand cramp - so being able to max out the size is a really big factorYou mean mechanically configurable, or configurable via software?
Most Logitech mice are very configurable via software, if you want to change button assignments, cursor speed, cursor acceleration, etc. Most also have weights inside the mice that you can remove if you prefer a lighter mouse.