-Do you want to get the most out of your phone by customizing it to fit your needs?
-Do you want to flash different kernels/ROMs to improve your experience using the device?
-Are you a geek who loves new stuff?
If you chose any of the above, then go for Android.
-Do you want something that simply works?
-Don't want to spend your valuable time by tweaking your device and always searching for latest ROMs/kernels?
-Don't mind the smaller screen?
-Want to be locked up into the Apple world/own other Apple devices?
If you chose any of the above, then go for Apple iPhone 5.
I myself have just bought Google Nexus 4 last month and it is a really great device I recommend you check out. Heck, if you live in the US you can get an unlocked Nexus 4 for $350.
In the future I might switch to Apple device (if they increase the screen size) because I am kind of addicted to flashing new stuff on my phone.