Dropping the phone: Some models of smartwatches in the Samsung and Apple line-ups feature a mobile network chip, allowing you to plug in a micro SIM card to make and receive calls, texts and emails and access the internet without being paired to your phone. It sounds great, but remember that the smartwatch has a very small battery, so relying on it for communications will drain the power quickly.
The top smartwatches that debuted at the 2017 Consumer Electronics Show included the Casio WSD-F20, Misfit Wearables Vapor and the Garmin Fenix 5 series. Apple released on September 22, 2017 their Apple Watch Series 3 model which offers built in LTE cellular connectivity allowing phone calls, messaging and data without relying on a nearby smartphone connection. 
The touchscreen, button, and dial (what Apple calls the “crown”) help you zoom in and out and move between apps fairly effortlessly. With this easy navigation it’s easy to forget we’re typing on a screen slightly smaller than an Oreo. In particular, we loved Apple’s app homepage, which displays all of the apps as icons in a honeycomb-like display. You can use the touchscreen to move around, and the dial to zoom in or pan out, to precisely tap on the one you want.
"Sport watch" functionality often includes activity tracker features (also known as "fitness tracker") as seen in GPS watches made for training, diving, and outdoor sports. Functions may include training programs (such as intervals), lap times, speed display, GPS tracking unit, Route tracking, dive computer, heart rate monitor compatibility, Cadence sensor compatibility, and compatibility with sport transitions (as in triathlons). Other watches can cooperate with an app in a smartphone to carry out their functions. They are paired usually by Bluetooth with a smartphone. Some of these only work with a phone that runs the same mobile operating system; others use a unique watch OS, or otherwise are able to work with most smartphones. Paired, the watch may function as a remote to the phone. This allows the watch to display data such as calls, SMS messages, emails, calendar invites, and any data that may be made available by relevant phone apps. Some fitness tracker watches give users reports on the number of kilometers they walked, hours they slept, and so on.
You won’t get much use out of an Apple Watch if you don’t have an iPhone nor any other kind of iOS-enabled mobile device. The same thing goes for the Samsung Gear Sport. While the Q Venture does feature some compatibility with Android and iOS devices, it won’t mix well if you’re a Samsung customer. The smartphone you use will ultimately determine which smart watch you get the most value from.
If you like traditional analog watches and want just a few smart features, the Cookoo 2 might be more appealing than its more full-featured rectangular competitors. Behind its hands is a monochrome display that delivers basic notifications: incoming calls (with Caller ID), missed calls, texts, e-mail, social media alerts (for WhatsApp, Line, QQ, WeChat, Skype, Facebook, Twitter), and calendar alerts. Just bear in mind that it's a very basic smartwatch, with little configurability.
Its only drawback is its use of Samsung’s own Tizen OS. Tizen is a custom OS that’s based on Linux. On paper it’s pretty good, letting you pair the Gear S2 with any Android smartphone, not just Samsung Galaxy phones. But it’s nowhere near as developed as Wear OS, which itself isn’t perfect. There aren’t nearly as many apps available as the Wear OS app store, but the core functionality is at least present from what is available.
Being able to customize the watch faces and layouts, made the Series 3 a shoo-in for our list of best smart watches. Much like you can customize the homescreen on your iPhone, you can change the layout of apps and even display the weather. While you can’t opt for third-party designs, you do have 12 different watch faces to play with. Tinker with color schemes, add or remove widgets (called “complications” on the app), and decide whether you want to have all twelve faces available on your watch (we always like having options), or cut back.
The Series 4 now has several new health-focused features, which are very intriguing, including the ability to detect when you fall and even alert emergency contacts if need be, as well as an electrical heart rate sensor that works with an app to alert you to heart health issues. The electrocardiogram (ECG) app has been certified by the Food & Drug Administration, but it's not out yet.
The headline features are the new ECG monitor that unlocks the ability for serious heart health monitoring. It's been FDA cleared, so the feature can be used to detect heart rhythm irregularities - however, it's only in the US only for now. There's also a new fall detection mode that can let users access Siri to contact emergency services or a emergency contact. Apple's new smartwatch offers groundbreaking features and an improved design that makes it the standout option for iPhone owners right now.
For deeper integration with your Android phone, you can give Google's Wear OS platform a try with Fossil's $275 Q Control touchscreen smartwatch. It lacks GPS and support for NFC payments, which is why the Gear Sport is a better fitness-focused smartwatch for Android users, but Fossil's Google Assistant integration and stylish design make it a solid contender. However, smartwatches with Qualcomm's new Snapdragon Wear 3100 processor start shipping in October, so you may want to hold off until we put them to the test.