There’s always been those who’ll use a trackball in preference to a mouse or trackpad. Other than aesthetics there’s very good reasons for this, not least that employing different controllers is an effective way to reduce risk of...
Trackballs and joysticks are mousing alternatives that require users to either roll a ball within a socket-like platform or shift a pivoting handle to move a cursor. Each can be used with a hand, arm, elbow, or foot by individuals with mobility challenges to navigate a computer.
I’ve looked around a bit, and found that Logitech still sells trackballs. The Trackman Wheel Optical is very similar to the Microsoft Optical Trackball. But the Marble Mouse Optical, which has a center-mounted ball, is quite different. It is symetrically shaped, to allow both left-hand and right-hand use. However, it doesn’t look like it will fit either hand nearly as well as the Microsoft Trackball Explorer fits the right hand. And what really kills it for me: there’s no wheel. I might still try one in the future though.