@Cana - I think you have to be clear exactly what you want from a device like that. I wear and have worn such a tracker for almost a year now and quite like it.
I initially bought it to track my sleep, but it's actually not super-accurate in that it has me "sleep through" various things, including getting up to make tea in the morning!
The activity tracker is quite amazing, in that it doesn't quite get gardening, and I can easily clock up many thousands of "steps" when hoeing.
In essence, it gives me an overview and it's useful sometimes to look back and see how active/sedentary I have been, in general terms, over a day/week or whatever. It can be set to auto-adjust my targets, or not.
About the best thing, valuable every day from the watch is it's pairing my phone, so whether I have my phone in my hand or not, or even when it's on mute, I know if I have any new messages or calls, due to the buzz on my wrist.
We've both recently been looking at Apple watches, but can't decide if the additional functionality is worth the cash.
If you know exactly what you want, then it's easier to create a shortlist.