I don't doubt loose buttons on the iPhone. Perhaps I've not noticed since the buttons are round and they always appear to be sitting perfectly straight. However, I've just read of loose and rattling iPhone 5s power buttons. I keep a case on both of mine so I've not noticed that either. The iPhone prolly does scratch easy but I could never use my phones without cases and screen protectors. Battery life? Well, since I have two iphones and alternate I've not been paying attention to battery life. The battery life certainly lasts me more than 24 hours but prolly because I'm not using the phones all the time (iPads filling in).
So none of these devices are perfect, it's just what ya like. I still believe Samsung could at least of given the Note 3 the Note 2's build quality...but I guess they needed to cut costs.
Sent from my iridium iPad Air LTE
All the home buttons on my iPhones (3G, 4, 5S, iPod touch 5th gen) have been loose or clicky and the home button on my 3G stopped working after a year. It doesn't really bother me too much but it happens.
I also heard stories of the iPhone 5/iPad mini getting scratched. My iPad mini and iPod touch 5th gen are both over a year old and are spotless. I take care of my devices and always have a screen protector and case. I only had my iPhone 5S for 28 days but it was still in mint condition.
As for battery life I'd say that the 5S is comparable with the S4, they both last a day with moderate use. I haven't had my note for long enough to make a fair comparison. Where the iPhone falls down is its lack of a removable battery. I was away last weekend and was using my iPhone a lot so the battery drained. I have a morphie battery pack but it didn't solve the problem. It took a while to re-charge and didn't have enough juice to completely charge the iPhone. I much prefer to have a spare battery. I had one for my S4 and a few for my original note. I didn't have to use it much with my S4, but was ideal for trips away.
In regards to build quality, yes the 5S looks better and is constructed from more premium materials. However, I don't find Samsung all that bad. Their designs are sturdy and stylish in their own way. They feel good in the hand. I'm. to sure if the iPhone feels good in the hand, especially after you have used a larger android device with a high quality screen. The iPhone then feels a bit toy like in comparison.
I think we are all different, for some people like yourself the iPhone is perfect.