First of all, in general the sleep tracking is just an indicator. If you want to track getting enough sleep (just the hours) you're good to go. As for sleep quality: I completely ignore that part. It's rarely consistent with how I experience it and feel fit for training..

That being said, even though garmin seems pretty close to being the standard for runners, I went for polar. Mostly because of the data collection policy but 'buy european' put in a lot of weight too.