Apple has continued its focus on its health focus with the Series 4. In addition to being able to detect a fall, this new Apple Watch introduces three heart-rate tracking features that will be available later this year. It lets you know if your heart rate is too low, it can detect irregular rhythms (which may indicate atrial fibrillation), and most impressively, it serves as an FDA-cleared electrocardiogram.
Samsung's Galaxy Watch, a Tizen OS watch (starting at $329), is our favorite smartwatch for Android users. In addition to up to four days of battery life and a great design, the Galaxy Watch offers built-in GPS, heart rate sensor, water-resistance, Samsung Pay support, plus a nifty rotating bezel for navigating the interface. You can also download music from Spotify to the watch for offline listening. However, you get far fewer apps than you would with a Wear OS watch.