I came back...
...to the 5s from the 6.
This will be my personal experience with the phone and in no way am I making any judgments. But others might be in the same boat so I thought I'd share.
I actually had a 5 before I switched to the 6. And I wanted to like it...I really did. A bigger screen seemed nice, especially since my sister still raves about her Galaxy S5. I could look past the ugly plastic antenna bands and the protruding camera; I would put a case on it anyway. And the battery on my 5 was beyond horrible at this point--I needed a new phone. So I picked up the 6.
Right away it felt slippery, even with a case on. I used the Speck CandyShell then switched to the CandyShell Grip briefly. I could use it one-handed...sort of. I had tested it out in the store before but never with a case, which added a little more bulk. My hands are a little on the small side for a guy and I found myself having to shift the phone in my hand to reach the top parts of the screen. Yes, I could use Reachability, but I felt that it was a lame compromise and it just got annoying to have the screen bounce up and down when I had to go back through many screens, such as in the Settings app. It didn't take that long to get my hand tired, especially with the phone being a little heavier than the 5. It's not a huge difference in weight by any means, but I could definitely notice it while using it on my commute one-handed. And I missed the sharp edges of the 5, which I personally liked...much better than the rounded edges of the 6.
Battery life was AMAZING. I wish they had made these batteries earlier. I also liked the new design of the earpiece and how it was more flush with the surface of the phone. But that was about it. I realized that a larger screen didn't really benefit me much in any way. I don't play games on my phone--the ones I do play are simple word or card games. I don't watch videos on my phone (I do that on my TV or laptop) and I don't read (I have a Kindle if I want to read). And so a larger screen, I realized, wasn't a must for me. I also realized (again) that Apple didn't do much to take advantage of the larger screen. Sure, I could see more text and display more icons (though I used the Zoomed view so it was the same as my 5) and things were a little bigger, but that was it. No split-screen like the 6 Plus even though I feel like the 6 could have handled it. Nothing really different that could take advantage of the larger screen.
These things made me realize that I missed my little phone. It was so much easier to use one-handed and it worked just fine for me, save for the battery. So I went to the Apple Store and did their first-ever (so the Genius said) exchange from a 6 to a 5s. It's a step backwards, but it was one I was willing to take. The phone feels so much more comfortable in my hand and I enjoy using it, which I think is important for a daily device. And it feels better in my pockets too!
I know eventually I'll probably move to a bigger phone, maybe when the 6 becomes free like the 5c. Until then, though, the 5s and its 4" screen is good for me.
End of my story...at least I got the white 5s, so that's a change (I had the black 5)!