The Apple Watch Ultra 3 is the no-compromise pick for athletes who want everything on one wrist. The titanium case and sapphire crystal display are built to take a genuine beating on trails or job sites, and 100m water resistance means swimming and diving are actually on the table, not just splash-proofing.
Precision dual-frequency GPS, Pacer, heart rate zones, and custom workouts make it a serious training companion across running, swimming, and cycling, and it goes further than the Fitbits on health monitoring, watching for things like irregular heart rhythm and signs of sleep apnea. GPS plus Cellular means it works as a standalone device away from your phone.
None of that comes cheap. The price sits well above either Fitbit here, and the 49mm case runs large on smaller wrists, worth trying on before you commit. For serious or outdoor athletes, though, it is a genuinely different tier of watch.