I just switched from Garmin, the heart rate tracking is much better during workouts on the pixel. Enjoying the first few days not needing a chest strap!
Garmin of course had a lot of extra details for running, but I've stopped needing that. It depends the type of fitness you're doing in the end.
I do everything from gym workouts, to pilates, jogging and even Mountaineering / long hikes. My Forerunner 305 needed a chest strap, but, my newer one doesn't (and I agree, the optical sensor, whilst I was skeptical when they were first released, are actually really awesome).
I guess I'm also a bit iffy about the battery life too. I'll need gps tracking, strava syncing, and heartrate tracking for 8+ hours per day I guess