I was using polar beats, However after the last couple android updates the app is freeing and not wanting to respond after running for 2-3 hours. I just got the wahoo speed sensor and Strava does no support it, so i am going to be using the Wahoo app and upload to strava. I am hoping to get a Wahoo Element Bolt in about a week and that should get rid of all my app issues.
Also don't forget to run Charity Miles. Free app, no cost, donates $0.10 per cycle mile to a charity of your choosing. I just start it and leave it when I ride.