Why I went for Galaxy S4 over the Htc One
Ok I know there's been tonnes of posts on this, but people still keep posting uncertain which to chose, so I thought I'd give my reasoning having finally had a detailed play with both.
Firstly let me get out of the way that I'm no fanboy/shill/whatever...I'm getting the GS4, but that doesn't hide the fact that it has lag issues, reported overheating issues, poor internal memory Etc. (the list goes on)...
GS4 - OK it's no masterpiece. In fact in black I personally think it looks awful and really cheap. It's kind of a blue/black see-through thing. On the other-hand I've never been a fan of white phones, but actually I think it looks quite nice. A lot of this is down to the fact that it's just a screen basically on a really thin sparse white body with silver accent. I don't love it, but I do quite like it.
One - I feel like I want to love it like everyone else does, but I just couldn't in the flesh (only saw silver, I'd probably like black may be better). Saw two demo models, one pristine, one scratched up with dirty plastic which I guess is what would happen months down the line if you don't look after it. Anyway, I found the front too busy (htc logo, silver, big black bezels), and while I can appreciate it, for me it looked better in the pictures.
GS4 - I'm a fan of amoled. The screen is great and is obviously bigger than the One, and I didn't find it 'dim' at all as some have said.
One - Great screen again, but didn't feel it as much tbh. Part of it is that the GS4 screen looks better in situ. I.e. The only thing on the front of the phone is the Samsung logo and ultra thin bezels. As I said above the One is quite busy, and even the nav buttons don't disappear like the S4s do.
Disclaimer - Almost every reviewer I've seen say they prefer the HTC One screen
GS4 - Ok here is the real deal-breaker. The GS4 feels really good in the hand. It feels lighter even though it's not by much, and I personally don't mind plastic. Sure I wish it was Nokia-style plastic, but it still feels good against my hand. But bigger than all that...it's set up for one-handed use. It can be woken by both home and side power button.
One - Yes the metal feels 'premium'. But it also feels cold, and it also felt a little sharp in the hand on the edges. The nav buttons are not ideal (though I think they're silly) I could get used to them. But the power button is beyond stupid imo. It makes it impossible to use the phone one-handed without shifting it up and down. It's an ergonomic nightmare, and I have fairly big hands. On top of that, it's really recessed just to make things even harder.
Didn't try out anything really, because I wanted to choose on the basis that I might flash stock or something eventually, and I didn't want to be swayed by any gimmicky SW that I may never use again. Although I have to say I really liked blinkfeed.
Anyway that's it pretty much, there's lots of other pros and cons either way that have been covered extensively. Let me stress again that the above is just my use scenario, and what swung it for me. Most professional reviewers and youtube reviewers all seem to prefer the One, even if it's not a by a long way.