Galaxy S4 or iPhone 5S?

I have a Nexus 4 right now, its ok but between the heat,bad camera and poor battery life I was thinking to upgrade.

My opinion on the two-

iPhone 5S:

Great hardware. Looks like it will be pretty powerful but for the same reasons as before the screen is to small and iOS is still to locked down even though iOS 7 was a step forward android is ahead.

GS4:

Great display and size, tons of features I just am a bit hesitant to switch because I have been on iOS for a long time

What do you think is the best option? Any complaints about the S4?

-thanks