I've used the Kensington SlimBlade Pro and their Expert Mouse Wireless. The Expert Mouse wins hands-down as far as ergonomics. But Kensington is awful when it comes to Driver support. I'll never buy another Kensington product again.
Unfortunately, Logitech is the ONLY manufacturer who seems to care about Mac users. They don't have a pure trackball but offer the hybrid
MX Ergo @varezhka mentioned. The Logi Options+ driver software is updated frequently and offers plenty of customization.
Logitech makes excellent quality products with two minor caveats... do NOT get anything with white-colored casing. Something about the plastics and coating they use is prone to discoloring/staining and you absolutely can not clean them off. Stick with the black color. Second, the MX Ergo, Ergo and Ergo Plus all use a crummy MicroUSB connector and the old USB-A receiver... which means you're going to need dongles/adapters if your Mac only has USB-C ports – one to permanently keep the receiver in and another one to charge the mouse.