The latest Apple optical wrist heart rate sensor is marginally more accurate than Garmin in some situations. But as a practical matter it's kind of moot because anyone who really cares about accurate heart rate data uses an electrical chest strap anyway.

> anyone who really cares about accurate heart rate data uses an electrical chest strap anyway.

I want to check, but not for exercise, for AF detection. Surely no one wears a chest strap full time.