The operating system you choose depends solely on the type of smartphone you have because the smart watch is paired with your smartphone. If you own an Android smartphone, your smart watch should have Android Wear or Tizen. If you own an iPhone, choose an Apple Watch. For example, the Samsung Gear S3 runs Tizen and is compatible with both the Android and iPhone.
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
You can also use devices that support the Google Wear operating system in conjunction with an iPhone as well as a Samsung Gear device that runs Samsung’s own Tizen operating system. But Google Wear and Tizen devices are designed to pair with smartphones using the Android OS, so you won’t get full functionality when pairing with an iPhone. For instance, some Android smartwatches carry Samsung’s smartwatch line-up and naturally enough, work best with Samsung smartphones, but are still compatible with Android-powered Huawei or Nokia phones.
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.