The MX Master 4 and Magic Mouse 3 both cost $100. They both pair with Macs. That is where the similarities end.
The MX Master 4 is a productivity tool. The ergonomic shape fills your palm. The MagSpeed electromagnetic scroll wheel flies through 1,000 lines per second. The thumb wheel handles horizontal scrolling. Three device buttons switch between computers with a tap. The battery lasts 70 days. It works with Mac and Windows. But it is large, heavy, and takes up significant desk space.
The Magic Mouse 3 is Apple’s vision of a mouse: a seamless touch surface with Multi-Touch gestures, now with USB-C charging (finally, on the bottom). It is thin, light, and minimalist. The gestures — swipe between pages, Mission Control — are intuitive once you learn them. But the ergonomics are divisive: the flat profile forces a claw grip, and the bottom charging port is still awkward.
Verdict: for ergonomics, productivity, and multi-device users, the MX Master 4 is the best mouse on the market. For Mac users who value Apple’s design aesthetic and gesture controls, the Magic Mouse is fine — but the MX Master is a better mouse.