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. 
Samsung released its Galaxy Watch, a follow-up to the Gear S3, a prior pick. The Galaxy Watch is available in 42 mm and 46 mm configurations, with either a Bluetooth-only connection or Bluetooth plus LTE from T-Mobile (at launch). The biggest update seems to be the battery life, which the company claims will last for days between charges. The Bluetooth version of the Galaxy Watch is available for $330 for the smaller version and $350 for the larger (46 mm) model; the 42 mm LTE version is available for $380 and the 46 mm is $400.
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.