Happy Garmin Fenix 3 HR owner here…great watch, week long battery life. A bit big but not too big. I wear it all the time as my main watch. I went for the Fenix due to superior navigation smarts:
1. ability out of the box to convert lat/long to a 10 digit OS grid reference, or the equivalent in many other countries. Use this in conjunction with map to get your position down to 1 sq metre.
2. altimeter (although like all altimeters this needs frequent calibration at known heights)
This is more useful for annual hillwalking trips to Scotland to bag Munros than biking but it would definitely come in handy on more remote rides in actual mountains. Most of my local rides I know where im going so don’t need it.
You might be able to add apps to the other watches in the Garmin range to achieve the same thing.
Otherwise it does all the usual activity tracking and steps / floors etc.
If you aren’t a navigation nerd like me, the other Garmin watches will be fine.
I actually like Garmin Connect these days and have an autofeed to Strava from it