I've had an iPhone for about 6 years now, ever since 3G as that was the first one actually worth getting. My upgrades were; 3G, 4, 5S. It always felt like I got an upgrade due to me skipping a model or two. I don't quite understand the hardcore Apple fans that go from 3GS, 4, 4S, 5, 5S etc and don't feel like they've really had an upgrade or not really notice much different from their old model. I mean what do they expect? I knew there wouldn't be much of a difference between the iPhone 4 & 5, that's why I waited for the 5S and I'm glad I did. The 'S' version just gives you that bit more that makes it all the more worthwhile.
I don't believe a bigger screen = better phone. When in truth a bigger screen = Bigger phone, which for me is a big no-no. I think the iPhone 5s screen is as big as it should get. I don't like the Samsungs screen size, the phone is far too big, may as well carry around a tablet at that size. The iPhone has lost it's mojo and is trying to compete with Samsung, hence the screen size gradually getting bigger and bigger.
After my soon to be 7 year long relationship with iPhones, I have decided to move on. Ever since Apple's father passed away, I don't feel like they are having the same effect, bridging gaps or taking control of the market and revolutionising technology like iPhones used to. They have become too 'sameish' and bringing out model after model with nothing to really get excited about. It is almost like the leader has now become the follower, struggling to keep up with it's competitors. They are no longer worth their overpriced costs.
I am waiting for the new Huawei phone, the one after this summers P7, as I believe they are going to take over in terms of functionality & value for money.