The Asus ZenWatch 3 was a previous top pick for a Wear OS smartwatch. As of now, it has reached the end of its Wear OS updates (after a very long delay getting to Android Wear 2.0). Its rotating crown does not actually work to turn or scroll anything on the screen. Its proprietary watch band connections mean that your options are limited to what is available from third parties on Amazon. And the watch is hard to find new.
Apple Watch (1st generation and Series 1) Apple watchOS No 8.2+ (1st generation) 10.0+ (Series 1) Apple S1 (1st generation) Apple S1P 4.0 LE ] From paired iPhone No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes IPX7 Digital 1.7 / 1.5 319x390 / 272x340 AMOLED 1.5 250 / 205 Lithium-ion 42 mm / 38 mm 12.46 / 12.3 36.2 / 32.9 Varies Yes Yes No
The era of the smartwatch is upon us – just look at the multitude of colourful straps and elongated or squarish screens people are wearing. From fitness trackers like the Fitbit and Garmin to the Samsung Gear and Apple Watch, there are a host of great options to combine fitness and activity tracking and message alerts on your watch, which incidentally will still tell you the time, along with the weather and even play your favourite music.
The Moto 360 was the first round smartwatch we got our hands (or wrists) on, and the design was a standout, for us. It looks like a traditional watch and fits more comfortably than rectangular smartwatches, but still packs the full functionality of an advanced smartwatch. Like the LG G Watch and Samsung Gear Live, it runs the Android Wear OS, allowing voice commands and pushing relevant information to the wearer.
The Misfit Vapor was originally launched with a proprietary operating system, but that was ditched for Android Wear 2.0. The Vapor has a 1.39-inch AMOLED display, Snapdragon Wear 2100 processor, 4GB of storage, 512mb of RAM, and a heart rate sensor. Those specs are fairly standard for Android Wear, but the Vapor also includes 5ATM water resistance which is a huge plus, and an assortment of software features added by Misfit.
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. 
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.
When we compared the storage space of the Samsung Gear Sport with the other contenders, it didn’t have the most. With 4 GB — only a quarter of what you’ll get with the Apple Watch Series 3 GPS — you will have to manage your apps so you don’t run out of room. If you like to carry all of your music with you and you have an extensive library, you might run out of space with the Gear Sport.
But smartwatches have the innovation advantage these days as most companies making such devices try to develop features that competitors don't have. As a result, fitness trackers have become a bit stale. And after wearing the new Charge 3 for nearly two weeks to see how well Fitbit's gentle marriage of smartwatch and tracker features turned out, it seems the form factor remains radically unchanged—but that's not a bad thing in practice.
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.