An excellent activity tracker that has good reviews. Tracks: Steps, Goal, Calories and Distance. The optical HRM on watches are unreliable, so if you want to do it accurately you can do it properly with this watch by pairing it with a chest strap. You don't need to charge it. It has a 12 month battery life which you can easily change when it's due.
Many rate it as good or better than the Fitbit Charge HR. Search Youtube for comparison reviews.
I've been keeping an eye on this and at $94.52 this is a bargain.
Actually you are wrong about watch type optical HRM not being as accurate as chest straps.
I believe there is comparisons between strap and Mio Alpha 2 which suggests they can do a optical hrm to be just as accurate.
http://www.wareable.com/sport/mio-alpha-2-review
I remember there was a graph comparison somewhere but can't seem to find with my phone.