I've been looking for the same. No one likes using a chest strap, but the wrist mounted HRMs are not as accurate.
The Scosche Rhythm+ seems to be a pretty popular alternative. Goes on your forearm, ant+/bluetooth, very accurate, less bothersome than a chest strap.
Pretty detailed review:
http://www.dcrainmaker.com/2014/05/s...h-optical.html
It's what I'm leaning towards and will link with my Garmin GPS watch.