One of the first, and some (like me) would say still one of the best, smart watches you can buy is the original (now renamed "Classic" Pebble. It isn't fancy like the new Apple Watch. And it doesn't have a touch screen like the many Android Wear watches now on the market. But it works with both Android and Apple smart phones and has week-long battery life. You can also shower with it (although I don't understand why anyone would wear a watch in the shower). But at least that means you don't need to worry if you get caught in a rainstorm without your umbrella (your phone may not fare as well, however).
The price of the Pebble has steadily dropped in the wake of new smart watch releases (including Pebble's own Time smart watch shipping this month to early supporters). You can now get the original Pebble on sale for just $79.99. At that price, it is a great introduction to the world of smart watches. I wear mine every day and find its handling of notifications from my Moto X Android phone to be superb. It saves me having to pull out my phone to check emails or texts and I can preset templates to send simple responsed to text messages directly from the watch. There are many watchfaces and apps available. My favorite watchface is YWeather. It shows me the time, date, weather, GPS location, and my phone's battery level.