I left the iPhone for customization reasons. I like, for instance, Nova Prime. Now mind you, depending on what carrier you're with, you have different options for customization -- and if you have KitKat on your phone, Google has already screwed you out of a major portion of the phone's functionality by locking off writing to the SD card (other than for a few, kinda crappy, native apps). Your carrier, if it's AT&T has screwed you out of being able to root the phone, which opens up a whole host of cool things you could do with it.
However, there are still a bunch of customizations you can do, and Launcher is a great way to start. Investigate widgets as well -- they're extremely useful. Maybe by the time you're familiar with how Android operates, Android "L" will be out, which will make your phone even better by returning SD card functionality. And eventually, someone smart will figure out how to root the AT&T phones again.