For me, it was how amazing Sync's navigation was. I found myself trying to use Sync's gestures in other apps--they're THAT intuitive and reliable. I'm honestly surprised Google or Apple haven't poached the developer to work on making the UIs of their built-in apps work more consistently.

For now wefwef is really good and does everything I need this type of app to do (mainly adjustable font sizes for my old man eyes with a minimalist interface which I prefer over the information overload that most seem to prefer, different strokes and all).