Even if there are "rubbish" apps in the App store, the fact that they need to be approved to get there gives more "polished" feeling over the android market. But whether it is true or not is a matter of discussion.
However the App Store has enough polished apps that work on all their devices that they can easily bury crap apps so they can only be found in narrow searches.
Android has a really hard time doing this because the best games don't work, or barely work, on older devices, or they are messed up on large screens, or they crash on some phone models, etc, etc.
So, on Android, the simple, addictive Indy games live at the top because the big games are sometimes providing a frustrating, rather than fun, gaming experience.