I checked this apps in Play Market, as was mentioned there is no Personal Zen, as no Brain HQ, other three are exist and Elevate have the best rating.
So for Play Market rightly:
- - Personal Zen
- - Brain HQ
- + Elevate 4.5 stars with over 1M downloads
- + Clockwork Brain 4.5 stars with over 100k downloads
- + Happify 3.6 stars with over 100k downloads
Yes elevate is most popular... My favorites were mentioned in the first part of brain trainer apps.