I agree with your decision, and I'm considering the Fenix 3 over the Apple Watch. For those who are fitness enthusiasts or athletes, the Apple Watch is not up to par - yet. If Apple includes GPS and an altimeter/barometer/compass in the future, then Apple will definitely steal away a larger share of the fitness enthusiast market.
The one thing Apple Watch doesn't have is ANT+ support. There is a huge market of ANT+ devices out there, but I don't think Apple will ever support ANT+.
As for the Fenix 3, the downsides as I see them are:
- Buggy software implementation, including GPS tracking (although this looks mostly resolvable via software updates)
- Poor sleep tracking functionality (again, could be improved with enhanced software functionality)
- No integrated heart rate monitor (AFAIK this would improve sleep tracking and daily calorie tracking; during exercise many would use a chest strap anyway).
Some other nice things about the Fenix: the watch screen is always on, it has multi-day battery life, and you can receive notifications from your smartphone.