I've had an AW and a Garmin for the past 4 year (now have a FR945 and AW6). I will say as a long time fence sitter, its not definitively greener on either side for me, just different pros and cons.
One thing I learned to enjoy with the Garmin was how 'quiet' it was on the wrist. No notifications buzzing away and a 10 day battery life. It doesnt require a lot of attention and feels more like a traditional watch experience. But still, I am in the Apple ecosystem and there's benefits to being all-in.
I've written a couple of long posts on the Garmin site and here comparing the Fenix and the AW6. It always comes out the same, the AW wins on paper, the Fenix wins my heart.
I really like the niche eco-system that the Garmin has. I lost 30 pounds with it. I feel loyalty, but, damn it is hard these days. I opened a ticket with Garmin about my headphones dropping (Air Pods Pro). I was told to wear the watch on my right wrist, so switch it to listen to music. I was told the same with the Marq which I bought and sold almost instantly. Ironically, it does fix the problem, but it's crazy stuff for a $1K watch.
But, it's not even a $1K watch. You need a strap, so toss in another $75 because it's wHR is terrible, and I guess I have to get a different set of headphones, noise canceling, so toss in another $250, and it's not even reliably syncing after the last update. Right now, for my needs, all it has over the AW is battery life, slightly better GPS and the ecosystem. But, WorkOutdoors is in the ballpark, Strong is much better than the Garmin strength app, I can listen to music/podcasts, and the battery while, frankly, pretty bad, is just functional enough. Plus, it can unlock my house, give me the weather (another half-arsed Garmin widget), answer calls, display my reminders, and more.
Garmin keeps adding features but they really need to add a QA team.