The Apple Watch's main flaw when it comes to workouts is that most third party apps suck. The built in workout app is the only app I've used that's rock solid, and gets you all the awards within Activity.app. It's where I track every run, ride, swim, walk, and hike.
But I still enjoy being social with my data, despite it being super personal and "private". I use Strava to track things like segments, improvements, and training for cycling and running, and enjoy having all my stats in one online place.
That's where HealthFit comes in. HealthFit is simply the best app for getting your workouts and health data out of the Health app, and into apps that are great for social features, but have terrible HealthKit implementations. [This thread has been going on for four years. I still get notifications about it.]
HealthFit is simply the best solution that I wish Apple would build into its app. It takes any workout, and [now even automatically], lets you sync it to third party service.1 HealthKit as an API is great to have, but when even the biggest players like Strava won't integrate with it correctly, or even allow you to import data from it, then you should write the feature yourself.
I also just came across Tempo which, in a similar vein to HealthFit, focuses exclusively on runs done with Workout.app, and allows a bunch of data points to be viewed from it. In my 5 minutes of using it, I've really enjoyed its visualizations so far.
Garmin Connect, Strava, TrainingPeaks, Final Surge, Selfloop, Smashrun, RunKeeper, MapMyFitness, MapMyRun, MapMyBike, Ride with GPS, Cycling Analytics, Today's Plan, Runalyze are among the apps listed that HealthFit will throw your workouts to. You can even export it as a FIT file. ↩