The only differences between the One and the S4 are that the S4 is plastic while the One is metal and the One has no removable battery/SD card. If that matters to you then get the S4. I tend to prefer Sense UI over Touchwiz, even though I have a GS3. Frankly either device trumps the iPhone as there are so many things you can do with a rooted Android device. Installing custom ROM's is a huge advantage that Apple will never have.
iPhone 5, it has everything I need and I've always gone with Apple's mobile products so I know my way around them, etc. Also, the auto-correct can be quite funny at times.