I've been generally happy with Xiaomi Mi Band. I used a Mi Band 2 for a couple years until it died and am using a Mi Band 3 now.
My biggest need was for a "silent" wakeup alarm since I get up so much earlier than my fiance. It does sleep tracking and a lot of phone features that I don't use.
The two biggest wins are (1) the price, and (2) the battery life. I paid like $40 for the watch, and $20 for a better band on Amazon. The battery on my MiBand2 lasted ~month and a half. The MiBand 3 is shaping up to be much less, but still 3-4 weeks between charges.
[Whoop](https://www.whoop.com/) has a lot of buzz right now and offers some interesting looking sleep insight. I haven't used one myself yet so I can't speak from personal experience.
Sleep tracking at $30/month? Are you joking? I don't think anyone moving from a Fitbit is going to be willing for that kind of $$$ commitment to track sleep!
Is there a comparable non-google device that does sleep tracking? My garmin watch is not a great replacement in that regard.