And before you rage at my post, please keep in mind that I do admit that the Galaxy S III is a great phone, and truly the best Android phone out there. It is finally smooth enough and fast enough. Just not nearly good enough to be compared to the iPhone. ; )
Neither platform is perfect, OP. Android still doesn't have a fully consistent UI interface and isn't quite as smooth as iOS (Though Android 4.1 and the latest apps are a big improvement from the Android 2.3.x days). iOS itself looks and feels a bit dated, with no widget support and a gimped notification shade compared to Android.
As to your points, a few of them are valid, and some of them you're really reaching because the iPhone 5 invalidates your point. If the iPhone 4/4S was so perfect in size and weight, then why did Apple work so slavishly to get the iPhone 5 thinner, lighter and taller? The point that any phone is too light is stupid at this point. Especially if you're going to use any sort of case on the phone, which adds to the weight.
If the Galaxy S III is too big for your tight pants, then something smaller like the HTC One S could be more to your liking (if Android's your thing, which for the OP, it isn't). I do find it annoying that there's no true flagship Android phone in the 4.3-4.5" size.
The "I need to borrow a charger" argument is also completely variable. First of all, the iPhone 5 does away with the standard Apple charger. Second of all, the Android phone uses micro USB, meaning any Android/Blackberry/Windows Phone/most Android Tablet chargers work fine, as do many bluetooth headset chargers.
-I do agree that the 4.8" screen isn't big enough for extended book reading. However, it's MUCH superior for surfing the web on than the 3.5" or 4" screens on iOS.
If the Galaxy S III is too dark for you, then FOR GOD'S SAKES TURN UP THE BRIGHTNESS!! Many of these phones (including iPhones) come pre-set for better battery life with power savings on and brightness turned way down. Once you go into the settings and tweak the brightness, the GS III's screen shines (no pun intended). Plus, you can easily tweak the brightness using a brightness toggle widget.
-As for the Samsung feeling like a cheaper device to the iPhone. That's certainly true, plastic doesn't have a premium in-hand feel. However, put a case on it and that goes away. The removeable back means you can put in a new battery (or have 2 batteries, which is awesome for people who are on their phone for hours a day), as well as a 32GB or 64GB micro SD card for dirt cheap. It's pretty awesome having 96GB on your phone, and the ability to interchange even more!
-Your signal strength results are completely in opposition to what I've found. Are both phones on the same carrier? I've found similar signal strength and performance on the iPhone and GS III, as well as call quality.
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Finally, this is just an issue of style. Stop using the word "perfect" so much in your comments. Once or twice is fine, but you used it seven times in your post! Even before the iPhone 5 came out, calling the 4S perfect in so many ways is a stretch. Now, it's ludicrous. Neither OS or interface is perfect; there are compromizes everywhere! The glass back makes the iPhone 4S look and feel premium, but also overly heavy and just look at what happens whe you drop it! Doesn't seem perfect to me!