I've been using a Kensington Expert Mouse Trackball for several years now. You might like it for a center trackball position. It also has a ring around the ball as a scroll wheel and four buttons which are easily programmable. A couple of AA batteries last me about a year on the 2.4GHz wireless, many months on Bluetooth. The ball comes out really easy so it's easy to take apart and clean. It has handled almost a decade of near daily use without any parts breaking.

https://www.kensington.com/p/products/electronic-control-sol...