I use a wireless mouse that has 4 options...left click, right click, scroll, or the scroll click thang.
I use to have a cord mouse, but then we got a new desktop and the cord wouldn't wrap around, so we use the wireless. I personally like it better, more room
However, I play with a standard 3$ mouse. Don't fall for the "gaming mice" out there. It will rarely make you get 10 more headshots every map ;S. But still, might improve for some people.