In my humble opinion. at the time Im a happy user of a Lumia 920, and an iPhone 5. And previously i was an Galaxy S3 and iPhone 4S owner. in my first experience the iPhone 4S against the Samsung, the 4S was unbeatable, it has a a better and faster reception, more battery life, and no lags comparing it Samsung S3. Now in this experience between Lumia and iPhone, both phones are completely equated in autonomy and Use fluency. both phones has no lags and respond immediately against my sisters S4. But, in this case (i don`t now why) the iphone 5 gets a terrible signal. its completely slow and most attempts to access internet or even whatsapp fail. While my 920 gets internet access without troubles and its GPS even without internet, is almost magical. Its true that windows phone doesn?t have the same quantity of apps that iOS or Android have. But that is change. After having Android (with the S3), iOS with iPhone 4S or 5, and now Windows Phone with my Lumia, i can tell that:
Equipment quality: Lumia. iPhone
Signal Reception: Lumia
Operative system stability: Lumia, iPhone
Operative system Usability: Lumia, iPhone
Battery Life: Lumia
Photo/Video Camera: Lumia
See videos: Lumia, S4 or S5
Games/Apps: iOS, Android (for now)
Editing Videos: iPhone, Lumia
Editing Audio: iPhone
Audio Recording: iPhone, S4 or S5
Create/see documents (with the official packages for each OS): iPhone, S4 or S5
Support and updates: iPhone, Lumia.
For all that. Im going to purchase a Nokia Lumia 1520 in these days. And give away my 920 to my uncle. I hope i have been helpful