Whether any of the apps are "good" is largely a matter of personal preference and what you want your watch to do. For me, all I want the watch to do is keep time and have a vibrate function. I use the Referee Watch App (by Winder) on my Garmin, and it does everything I want--and does GPS tracking on top of it, which is just gravy. The ref six app can also do more in terms of tracking things in the game. For me that's pointless as it is easy to do with pen and paper and I don't have to mess with my watch.
But if you're just starting, I wouldn't see the watch as a place to invest--start with a cheap digital watch with a stop watch, and think about investing in more for a watch once you decide you're in it for the long haul. You'll also have a better idea of whether you want to do more on your watch than keep time.
