Pebble (watch) was an innovative smartwatch that raised the most money at the time on Kickstarter reaching $10.3 Million between April 12 and May 18, 2012. The watch has a 32-millimetre (1.26 in) 144 × 168 pixel black and white memory LCD using an ultra low-power "transflective LCD" manufactured by Sharp with a backlight, a vibrating motor, a magnetometer, ambient light sensors, and a three-axis accelerometer. It can communicate with an Android or iOS device using both Bluetooth 2.1 and Bluetooth 4.0 (Bluetooth Low Energy) using Stonestreet One's Bluetopia+MFi software stack. Bluetooth 4.0 with low energy (LE) support was not initially enabled, but a firmware update in November 2013 enabled it. The watch is charged using a modified USB-cable that attaches magnetically to the watch to maintain water resistance capability. The battery was reported in April 2012 to last seven days. Based on feedback from Kickstarter backers, the developers added water-resistance to the list of features. The Pebble has a waterproof rating of 5 atm, which means it can be submerged down to 40 metres (130 ft) and has been tested in both fresh and salt water, allowing one to shower, dive or swim while wearing the watch.
16GB Capacity/ Supports Voice And Data Over LTE And UMTS/ Built-In GPS And GLONASS/ Dual-Core Processor/ W2 Chip/ Barometric Altimeter/ Heart Rate Sensor/ Accelerometer And Gyroscope/ Water Resistant 50 Meters/ Ion-X Strengthened Glass/ Ceramic Back/ Wi-Fi (802.11b/g/n 2.4GHz)/ Bluetooth 4.2/ Up To 18 Hours Of Battery Life/ WatchOS 4/ Band Fits 140-210mm Wrists/ Space Gray Aluminum Case With Anthracite/Black Nike Sport Band Finish
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.
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. 
Smart watch Company OS Android version iOS version CPU Type Bluetooth NFC Developer Options GPS Notify Link Loss Alert Notify Missed Call Notify Timer Notify View Content Call Conversation Find My Phone Voice Control Respond to Notifications Notify Sound Notify Backlit Screen Notify Vibration Ambient Light Sensor Gyroscope Magnetometer Multi-touch Accelerometer Dust and Water Resistance Clock Display Type Screen Size, Inches Screen Resolution, pixels Pixel density, ppi Display Technology Average Battery Life, days Battery Capacity, mAh Battery Technology Case Diameter, mm Case Thickness, mm Wrist Band Width, mm Weight (main unit+watchband), g Wristband Options Replaceable Wristbands LED Flashlight
Google confirmed to Tom's Guide that the company won't be releasing its own Wear OS smartwatch this year. The news comes after months of rumors that a Google-branded Pixel Watch running on Qualcomm's latest processor would be launched at Google's October hardware event. Instead, Google plans to focus on adding features to Wear OS on the software side and support the companies who are currently making Android smartwatches. Google's hardware event is Oct. 9.