Too Long; Didn't Read
For apps made by personal developer, simplicity is of the utmost importance. Unless you are a huge company like Adobe or Microsoft, it’s obvious that you lose against other services if you competed by number of features. Your app’s features won’t kill competitors. So leave the difficult things to others and focus only on the problems you would solve. If you have a clear image of what you want to make, you can easily determine which features should be added and should not be added.