Since I first tried a thumb controlled trackball, almost 20 years ago, it's been impossible for me to imagine ever going back to an ordinary mouse. Arm/wrist movement is just bizarrely inefficient and unergonomic in comparison. The only thing I dislike is the limited number of high quality models to choose from. Right now I have a Logitech MX Ergo which is fairly good, but I wish there were more alternatives.