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 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 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.