I have a few questions for you.
What is the PPI of the S3 and that of the iPhone? Once you have the answer, factor in screen size. Now compare to the PPI of the ipad and it's size. Learn anything?
Which display is thinner and conserves battery life more: IPS or Pentile?
Which camera sensor is better: the iphones or S3's?
Do you have a case on your iphone?
Touchwiz isn't a factor. If you don't like it, you can easily change it. Can you change iOS?
When you can answer these questions, reread your post.
306, 326, 264. I don't see anything meaningful across two smartphones and one tablet.
First, PenTile is not a display. PenTile is a subpixel layout and is not unique to just AMOLED panels. As for battery life, PenTile has nothing to do with battery life. AMOLED and IPS, however, do make differences in battery life performance. But a display should and is not judged solely by power consumption. If all we cared about is power consumption, let's keep using those monochrome displays in the old Nokias (the name of the type escapes me at the moment).
Sensor doesn't matter. Is that how you compare cameras? This sensor has better specs therefore it must output better photos? NO. It's the firmware that drives the sensor that is slightly more important. A good sensor with mediocre firmware is worse than a slightly lesser sensor with excellent firmware.
No, I don't have a case on my iPhone. Glass and steel make for a durable and structurally solid device unlike cheap plastic.
TouchWiz IS a factor. Sure, us geeks types have the know-how to root and flash different Android builds but MOST people don't know, don't care and most importantly, don't want to care. So for the vast majority of smartphone owners, what they get when they buy it is what they use. For us, TouchWiz is NOT a factor. But for most people, it is. I personally like vanilla Android. It looks very elegant, simple and beautiful. It's also very smooth and complete-feeling. For that reason, I usually recommend the Galaxy Nexus because it's $350 for a completely unlocked device that will always get the latest software updates.
Build quality is just fine. I don't understand GS3's bad rep for build quality. Feels solid in my hand, no creeks or any looseness, home button feels solid, volume and power buttons are average but seldom used. The front glass actually has a smoother feel than the iPhone glass.
I like TouchWiz, don't see any problem at all with it. You didn't actually give a reason to state that it's garbage.
The display is excellent. I'm very satisfied. It's saturation actually makes watching vids better than on a retina display.
Mediocore Camera???? Now your just trolling.
More than 5 of my friends had (but later returned) the GS III from different carriers and even different countries/carriers. All but one of them had loose-fitting buttons, chassis, components, back cover, etc. And every single one of them creaked when they were using it normally (i.e. not specifically trying to find a spot that creaks). Volume buttons and power buttons were hard to press, sometimes loose-fitting. Look at HTC's build quality. Also Xiaomi and Lenovo (yes, they make smartphones but only in China). Another good example is Nokia and BlackBerry. That's quality. Not Samsung plastic crap.
TouchWiz does two things I don't like. It slows down the entire OS. It slows down OS upgrades. And this my personal opinion, it looks very ugly. The first two statements are 100% fact while the last is just my personal opinion.
If you read on a smartphone, then PenTile is horrible. And the colors are disgustingly fake for AMOLED screens. IPS is the gold standard. I'm glad HTC One smartphones have IPS. Many of my friends took their GS II back to the store because they couldn't stand the color inaccuracies. It either looked way too disgusting and/or looked much worse when they take a photo and transfer it to their computer or upload to facebook and realize it's not what they saw on the phone.
Camera is mostly hindered by the clunky Android UI. The sensor itself should perform quite well.
nom nom