I’ve been using Gleeo Time Tracker - Timesheet too, for over a year.
The app is very good, and has almost 5 stars on the Android Play Store. It’s also free, unlike most of the alternatives mentioned above. It can export data, and has its own reporting function.
I’ve found that time tracking itself takes a little more time than I anticipated - about 5 - 10 minutes per day if you want to track activities with actionable accuracy. Also, the mere fact of using a time tracker made me more aware of how I was using my time, and more focused (see the Howthorne effect).