Ok, so I've been reading everything I can about the One and the S4 for the last month solid, and I couldn't for the life of me decide which one I wanted. Most of this indecision was caused by thinking that the 2 screens were very comparable, save for the S4's being a tad bigger.
So I went to the AT&T store today to finally get a look at them in person. Let me just say, that anyone pretending like the One's screen is anywhere near as good as the S4's is smoking crack.
I picked up both phones together, turned the brightness all the way up on both, and played with both for a minute or so. The S4's is so much better that it's not even a contest. It's twice as bright, and the blacks are pitch black. The One's screen looked dull and washed out in comparison. It was enough of a difference that I didn't even care about comparing anything else about them at that point.
I'm also a lot less put-off by the Samsung interface than I figured I would be. My only complaint about it is that it just feels kind of cheap in your hand. I upgraded from an Inspire 4G, and the Inspire feels like a solid piece of machinery that could be abused (and it has been, I've dropped the living shit out of it more times that I can count), and the S4 feels like a thin piece of plastic that you could break in half if you aren't careful. Maybe I just like the solid feel of the Inspire, and don't care about how heavy it is, but the feel of it definitely eases any worries that you might break it.