I've been switching between iPhones and Android phones every 6-12 months for the past 7 years (currently switching off between the HTC One M7 and iPhone 5S and here's my take on it
Pros
iPhone just delivers most of what you need in a trouble free, aesthetically pleasing, "it just works" package that you just can't get in Android. Timely updates, great hardware, and of course the far superior App Store.
Hangouts doesn't come anywhere close to iMessage despite what people say.
Superb camera, great accessory support, great ecosystem, seamless integration if you have other Apple products. And iOS8 seems to be headed in the right direction and the jailbreak community is always fantastic. Widgets, theming, better multitasking, file system and many other things have been available long before they were officially released.
Cons
The static row of icons get extremely boring to look at which is mostly the reason I switch around.
The tiny screen. 4" was a decent upgrade from 3.5" but it still wasn't enough.
Still can't set default app permission except for browser and maps via jailbreak
Having to use iTunes
Overpriced storage options
low RAM
Android
Pros
Insane number of options for any type of phone you want
options for removable storage
Great customization within the OS
Certain phones have great specs you won't see on an iPhone anytime soon (1440p display, huge battery,etc)
A file system
A back button
'Better' multitasking
Google Now
Awesome support for media. Plays anything you throw at it seamlessly without having to jump through loopholes like in iOS
Cons
Most if not all Android phones have pretty bad design in hardware. Personally plastic just doesn't do it for me when I'm paying 650-750 dollars for a phone. Even the HTC One while it looks decent still feels like a step behind the iPhone
Play Store doesn't have a lot of the greatly designed apps you can find in the App store especially games
Skins. God I hate these things. Sense 6 is actually pretty nice but everything else I've used has been utter shit and ruins the experience. ESPECIALLY Touchwiz. You can cover it up partially (only the home screen) with a launcher but the rest of it still haunts you
Bloatware. Unlike the iPhone, the carrier and manufacturers have no restrictions on what they can put on the phone and 99% of the time, it's garbage
TLDR version
All in all, Apple provides the best all in one package imo. Android has some phones with certain specs that are better but usually something else is always lacking. Basically just decide what features are more important to you and go from there. I'd recommend going pure Android via A nexus device if you decide to go the Android route. DO NOT go Samsung.