I’ve been using a Pebble smart watch for about 2 years now - I got the original Pebble 2 years ago then upgraded to the Pebble Time when they had it on Kickstarter a year ago. I absolutely love it and feel lost if the battery dies if I’ve forgotten to charge it, every time I get any sort of notification on my phone and I’m not at my desk, I just check the watch. Oh and when I talk about battery life, a Pebble Time lasts up to 7 days on one charge, yet still has a colour screen (the original Pebble lasted up to 10 days I believe but didn’t have a colour screen). It uses a colour e-ink display so doesn’t consume battery to keep something on the display, whist you can clearly read in direct sunlight and has a backlight for use in the dark. So forgetting to charge is usually because I’ve forgotten to plug in that night since it’s not needed daily like most other smart watches out there!
Pebble works on both Android and iOS. AND it costs only $149. There’s lots of apps available. You should definitely check this out.