Trackball ofc. Seriously though any mouse as long as it doesn't have terrible issues will do fine. Sure there are mice that have "better" sensors than others, but its not a big deal anymore at this point, just stay away from laser mice and you should be fine. Find the shape that works best for you, that will be one of the things that makes the most difference out of any.
Keyboard doesnt even matter on gunz tbh. You can play it on an old dell and be amazing or play it on a really expensive mechanical keyboard.
