It's mostly just a debate of iOS vs Android, though if I went to Android it certainly wouldn't be a Samsung device. I'll try not to get into the OS comparison too much but in my opinion:
- Better Camera
- Better performance (faster, smoother. Touchwiz is a mess), The iPhone has been "buttery smooth" since the beginning, closest thing to that on Android is the Nexus, not Samsung and their bloat.
- The ecosystem: Messages, Photos, Safari web browsing, iTunes, all synced across my iPhone/iPad/Macbook. This is where Samsung, Microsoft, and other companies are so far behind Apple that it's ridiculous. Their products vary widely and are all over the place while Apple has created a tightly knit, integrated system across their product lines.
- Battery life. From my experience the iPhone still gives superior battery life to the Androids I've used except for the Motorola Razr series and Note. If you turn off all the settings and tweaks that are supposed to make Android so great then I suppose you could get your battery life to equal the iPhone
- Reliability/Customer Support: Apple has tons of stores all over. Even if your iPhone happens to be out of warranty you can still take it to an Apple store and they'll diagnose your problem for free and attempt to fix it for you. If it's beyond fixable then you are offered an out of warranty replacement right there on the spot without having to drop $649 for another one. Your Galaxy S5 past that one year mark? Then pull out your credit card and fork over that $600+ for a new one. Besides that, good luck even getting an Android OEM to acknowledge your problem if the device is over a year old. There are no stores either so it's a mail-in and wait type thing.
- Last of all, it sounds cliche but everything just works. New iPhone comes out, I just restore from my old backup of the previous model and everything is there again just as it was. Been doing this since the iPhone 3G. Still have messages that go back to 2008 on here. Android still lacks that type of full backup system in 2014 that Apple already had in 2008. Right out of the box the music, messages, web, photos, etc. do their job. When I used Android the out of box experience was clunky and I had to dig through and find third party apps and tweak various settings before finally getting the device to an optimal state. I don't feel like tinkering with and modding my phone, I prefer it to just work.
The S5 has a better camera than the iPhone 5S, and the battery life slays the 5S. With everything switched on too! I'm not going to contest the other things you say, but these two issues can be discounted out of hand.
Samsung phones, for all their plasticcy Touchwiz badness, have always had great cameras, great screens and that fantastic removable/user replaceable battery. The battery thing by itself makes them a strong contender if you keep your phones for longer than a year. No more worrying if it's an app, or booking a 'genius' appointment to check your battery. Just replace the thing yourself, and with a genuine Samsung battery.