because iTunes sucks on windows and mac, it requires higher RAM and CPU than crysis 3 at ultra, I want to use spotify as my main music player on the iPhone (only playing local files) can it be done?
This is true...to sync your own music on spotify's iOS app, you need to have premium. With just the free account all you can do is play the radio (think Pandora).
If you don't like the stock Music app, you can sync your library and play using Amazon's cloud player app. It has a nice interface.