I am not really qualified to answer this question because I have never used Google Fit, but I love the S Health app. I think I looked at the Google Fit app but it did not look like it offered as many options as S Health. Of course that was a while ago and maybe the app has been improved. I especially think if you are using a Samsung phone S Health is best because of syncing. I also do not notice any drain on my battery due to S Health.