I use an Android and I like it. Mine is a Samsung Galaxy III. The Galaxy IV is out but I'm not really up on what improvements it offers.
You can get a Galaxy III at Costco for about $39 if you buy a 2-year contract with AT&T or Verizon. You can have multiple email accounts, holds about 4 GB of music, photos, etc. The camera takes great pictures. It does voice-to-text translation, meaning you can speak into it and it will take dictation, so to speak. It's very handy when texting people. The screen is larger than an iPhone 5. It's flatter than an iPhone and it fits very nicely in the front pocket. If you make certain to dedicate one front pocket to the phone and nothing else, it'll keep the surface from getting scratched.
My only criticism is a mild one. Because it's so thin it's sometimes difficult to hold in one hand without touching the edge of the touch screen. As for security, you can configure the device with a passcode to use it, but even if it's locked there is still a dial pad that will allow you to make emergency calls only, like 911. Also you don't have to enter the passcode to answer an incoming call.
iPhones are very popular, however I've never owned an i-anything. I'll let the others speak of them. Good luck with your decision.