After approximately four months with the GS4 on Verizon, I'll be picking up an iPhone 5s on Friday (fingers crossed that I can even find one). I've dabbled in Android for the very last time and consider it to be the clearly inferior platform. Here's why:
1. The thing I do most on my phone is text friends and family, with most everything else being a distant second. iMessage on iOS has such a huge advantage over the basic SMS texting available on Android that it isn't even funny, especially when you're sending pictures or video which I frequently do. Add to that the effortless synching of iMessages across the entire Apple ecosystem (from Mac to iPhone to iPad, etc.), and Android simply can't compete. Plus, when you get right down to it, I hardly know anyone who doesn't have an iPhone so everyone uses iMessage.
2. The thing I do second most on my phone is listen to music. Again, Apple has a huge advantage over Android in that Apple invented the iPod and continues to produce the best music player by a wide margin. Nothing I've tried on Android (and I've tried ALL the 3rd party music apps) comes close. From displaying album artwork to displaying alerts during music playback (especially in the lock screen mode) to synching everything effortlessly with iTunes - the iPhone continues to be the leader for music lovers IMO.
3. The thing I do third most is use social media apps and various other sports/news apps. Almost to an app, the iOS version is better in that it crashes far less, is more fluid and intuitive, and almost always uploads superior pictures, despite the pictures taken by the GS4 being huge and vibrant. I have no idea why that last gripe is the way it is, but that's simply been my experience.
4. Yes, the screen size of the iPhone leaves a lot to be desired. There's no avoiding that. However, the large size of the GS4's screen is really hampered by almost zero visibility in sunlight and poor touch responsiveness when compared to the iPhone. Unless you can palm a basketball, you'll probably need to use two hands on the GS4 and other giant Android phones. However, if you don't touch what you want exactly spot-on (with the phone braced with one hand and your free hand doing the selecting), the screen simply isn't as responsive and accurate to the touch as the iPhone. Don't even get me started on the poor screen sensitivity's effect on text entry and lousy auto-correct and auto-prediction...
5. Lastly, there is no equivalent of the Find My Friends app on Android. When you have family, friends, children, and others all scattered around, it is an absolutely invaluable tool for when you need to keep tabs on someone, like during car/air/train travel, at sporting events/concerts and other large gatherings of people, or just on the commute home. Again, Android can't compete. Although the Google Latitude app existed briefly, if you enabled location reporting so that the app functioned like FMF, the phone's battery would be dead before you set it down.
There are definitely things about the Android that are great and that I will miss. Full-featured Google Search (and accompanying widget) are great, as are Google Maps, the GMail App, snappy camera, and fully customizable user interface via 3rd party launchers. However, for what I use a phone for most, Android is still playing catch-up and probably always will be.
The analogy I'd use here is this - iOS/Apple : Android/Samsung/HTC :: Ferrari : Hennessey Motorsports. Yes, the super-tuned Hennessey sports car (take your pick of which one) can match the performance of and typically exceed that of a Ferrari on the racetrack. However, the Ferrari can't be touched in terms of overall taste, fit, finish, and class.