I began using an Apple Watch earlier this year (not just for golf). For golf I've been using GolfShot, seems good so far. There are loads of apps out there, but I wanted to make sure it didn't depend upon getting GPS from the phone. Using the watch GPS was a requirement for me as I keep my phone in the bag not my pocket. Using the Watch GPS it's always with me. There are others though, and I'm always open to alternatives.
Apple Watch tip - use a 'sports' band when golfing. When I used my magnetic band it would loosen up a bit when I swing. Just enough to sometimes allow the watch to briefly 'jump' off my wrist. This resets Apple security and I would have to login to the watch again. Annoying. A Nike sports band solved the problem.
I have a friend that really likes the Bushnell Phantom 2. Seems a good solution for those that do not want to wear a watch.