Why did I leave iOS? As far as functionality goes, no reason really. iOS is great, it just works. Yes the Maps suck, but that's just one program that is easily replaced with another. The reason I wanted a new phone to begin with is because my 4 has a cracked screen. I'm capable of replacing the screen (I replaced the screen on my gf's 4S), but since the Lumia was coming out I thought I would wait. I liked the Lumia because of the new OS, the supposedly awesome camera (photography is a hobby of mine), and honestly I wanted to help Nokia get back in the game. I was bored with iOS. It's based (visually) on OS X, which is over 10 years old now.
So anyways, turns out I got a dud. Originally I was going to return the phone and just repair my 4 for $30 bucks. Unfortunately the Lumia's screen size and speed spoiled me. My 4 looks tiny and feels slow. Ok then, I'll pinch my nose and buy the 5. That's what I did. So far so good. Another reason I bought the 5 is because after using the 4 again, I realized that I prefer the narrower overall dimensions. It feels better in my pocket.
As far as Android goes, I just feel that it is a kludge. It's sluggish. Whenever I say that, people ask "Well are you on Pancake or Buttermilk Biscuit?". To me, the OS shouldn't have to be overhauled multiple times a year.
In case you can't tell, I treat my phones as an appliance. I want to get in and get out so I can continue doing what ever it is I'm doing.
If that seems trollish to anybody, then so be it. I thought I would share my experiences. That's what discussion boards are for.