Bottom line: Some fitness trackers work equally well with an iPhone or Android device, but some smartwatches are built to pair with Android phones so you won’t enjoy full functionality and pairing on an iPhone. The Apple Watch only pairs with the iPhone so is off limits to Android users. Your existing phone choice will play an important part in choosing a smartwatch. You can check your smartphone’s compatibility with a range of Google Wear-powered smartwatches at g.co/WearCheck
If you want the app, notification, and style advantages of an Apple Watch but need better fitness tracking, you can upgrade to the Apple Watch Series 3 and get built-in GPS, as well as waterproofing that allows swim tracking. But the Series 3 costs more than a fitness tracker or even many running watches, and it still has compromises compared with a dedicated fitness tracker, such as a lack of dedicated physical buttons. We think serious athletes are better served by a fitness-specific device.
The Apple Watch Series 4 is now on sale, and it's the best smartwatch you can buy right now. The redesigned device, which starts at $399 for the GPS model and $499 for the cellular version, is the best smartwatch you can buy. It has a larger display and slightly bigger case size while retaining the same rounded square design the watch is known for. Even more importantly, Apple received FDA clearance for a new electrocardiogram feature that can take a 30-second EKG and diagnose atrial fibrillation.