With tools to monitor heart health, stress management and even skin temperature, this is a bit like having a medical assistant around your wrist at all times (though of course it's no substitute for your regular doctor). This is the second generation of Fitbit's health-focused smartwatch, and the updated interface and the return of the physical navigation button make this wearable particularly appealing -- especially at this price. Besides keeping a close eye on atrial fibrillation (heart rate irregularities), this Fitbit includes a cEDA sensor that detects electrodermal activity, which often correlates to your body's response to stress. You can also see your nightly blood oxygen levels at a glance. 

It still has all the great features the first-gen Sense offered, like built-in GPS for hikes, biking and driving. The watch also has Amazon Alexa built in for news updates, bedtime reminders and alarms, and it can control smart home devices too. The smartwatch comes with a variety of clock face options. One battery charge lasts six full days, and a full day's charge takes only 12 minutes.