The operating system you choose depends solely on the type of smartphone you have because the smart watch is paired with your smartphone. If you own an Android smartphone, your smart watch should have Android Wear or Tizen. If you own an iPhone, choose an Apple Watch. For example, the Samsung Gear S3 runs Tizen and is compatible with both the Android and iPhone.
If you don’t need your smartwatch to look business-casual, you want more fitness and exercise features than our top pick, or you’re a Samsung loyalist, the Samsung Gear Sport is a better pick for you. (You can use the Gear Sport with non-Samsung phones, but doing so requires that you install at least four apps.) The Gear Sport handles all the casual notification and message-triage functions of a smartwatch about as well as our top pick—with the exception of voice transcription—but it adds heart-rate monitoring, GPS tracking, swim tracking, and built-in reminders to move throughout the day. It doesn’t do all of these things perfectly, but it does just enough to make for a generally useful smartwatch, with great battery life and a clever interface.
On 9 September 2014, Apple Inc. announced its first smartwatch called Apple Watch to be released in early 2015. On 24 April 2015, Apple Watch began shipping across the world. Apple’s first try into wearable technology was met with considerable criticism during the pre-launch period, with many early technology reviews citing issues with battery life and hardware malfunctions. However, others praised Apple for creating a potentially fashionable device that can compete with "traditional watches," not just the smartwatch industry in general. The watch only turns on when activated (either by lifting one's wrist, touching the screen, or pressing a button). On 29 October 2014, Microsoft announced the Microsoft Band, a smart fitness tracker and the company's first venture into wrist-worn devices since SPOT (Smart Personal Objects Technology) a decade earlier. The Microsoft Band was released at $199 the following day, on 30 October 2014.
My personal favorite watch for Android on the market today actually isn’t an Android Wear device, rather coming from Samsung and running atop Tizen. The Samsung Gear S3 Frontier is all the smartwatch you’ll ever need, with a sporty, circular gray design with a 1.3-inch Super AMOLED display that is the best I’ve personally ever used and is protected by Corning Gorilla Glass SR+.
Our top pick for most people is the Apple Watch Series 4 with GPS (starting at $399), which has a huge display, ultra-fast processor, Raise to Speak Siri, fall detection and a built-in electrical heart rate sensor for taking on-the-go electrocardiograms. It also runs watchOS 5, which makes the watch even more useful with automatic workout-tracking, offline podcast playback and a Walkie-Talkie voice chat feature.