I've seen you post your use case in a bunch of places and it raises the question, where / how do you manage your data? Do you have a single repository that you funnel all your stats to (like Garmin Connect, Strava, Apple Health) and if so, what shortcomings do you see?
I've been Garmin for the last 2 years and the nice thing is they have all their data in one spot without the need for a bunch of 3rd party apps. I've also tried AW/Wahoo combos and end up needing all these extra apps (RunGap, Autosleep, Strava, etc) to move all my info around. Drives me nuts.
Good question. I prefer the Garmin repository due to its mobile app and web options.
For sleep I prefer Garmin's presentation, especially now with Pulse Ox and respirations, but I do use Autosleep with the AW. I've worn them both together a couple nights and the Garmin is right on for me (or at least consistent with AW and Autosleep).
If I wear an AW for an extended period (I no longer do), I have to live with Apple Health and the Activity app to see move/exercise/stand, steps, etc. I just don't prefer move/exercise/stand goals with Apple since I'm moderately active with 4-5 activities at least per week. I like floors and steps, and intensity minutes but prefer the activity burns and achievements, and all that data. Also run with Scosche HR, Tempe sensor, Stryd footpod, you get the idea. GEEK!
I'm mainly concerned with activities, and whether I wear an AW or Garmin (or both) for a run, I use RunGap to get the data to Apple, Garmin, Strava and Runkeeper. Wife and stepson use RunKeeper (stepson runs a 5K in 17 minutes). Few other friends use Strava. When I use AW with Gymaholic for weights (love the app), I use Rungap to send the strength training data to Garmin/Strava. When I use Garmin for a run, walk, ride, I use Rungap to send to Apple/Strava/Runkeeper. Sounds hard, but only a few finger taps on the phone.
Edited to add: When I wear a Seiko, Luminox, Citizen, etc., I wear the Vivosmart 4 on the other wrist to keep up HR, steps, floors, etc. That's a newer thing having just added the VS4.....