Garmin vs. Apple Watch vs. Coros: Best for serious endurance training?

Okay, so my old fitness tracker is on its last legs, and I'm ready to upgrade to something serious for my endurance training. I'm talking about accurate GPS, reliable heart rate monitoring, long battery life, and good metrics for tracking progress in running and cycling.

I've narrowed it down to the usual suspects: Garmin, Apple Watch, and Coros. I know Apple Watch is great for smart features, but I'm worried about battery life on longer runs/rides and if its GPS is truly on par with dedicated sports watches. Garmin (like the Fenix or Forerunner series) seems to be the gold standard for endurance, but some models can be pricey.

Then there's Coros, which I've heard good things about for battery life and GPS, often at a slightly better price point. For those of you who are serious about your training, which brand/model do you swear by and why? What features are absolutely essential for you, and which ones are just nice-to-haves? Any specific models you'd recommend or warn against?

For serious endurance, Garmin is the undisputed champion, IMO. Their GPS accuracy is top-tier, and the battery life on something like a Forerunner or Fenix is insane. You can track multi-day events without charging. Apple Watch just can't compete there for ultra-distances.