Please keep in mind that whenever you use a health or fitness related app, you are paying with your personal data. In almost all cases, the use of the iOS fitness API comes along with the need to share your health data that is stored in your phone (and to an extend in iCloud). You can’t really get around sharing it with Apple, and hopefully they stick to their promise to keep it safe and don’t sell it further.
But every new fitness app asks for access to health data again. And again. And again. You have to ask yourself: is that fancy third party pedometer app really that much better than the built-in Apple function?