The Galaxy S4 is everything a phone should be.
Yes, the HTC One looks good, has fancy speakers, and draws out the pity of many a soul, but in my humble and honest opinion, most of the aspects that people point out as being advantages over the S4 simply aren't practical.
Before I continue any further, I'll just note the things that I do grant the One over the S4:
-The speakers. While I never do and never will use the speakers on my phone, I have to admit that the One's speakers are indeed of a very high quality. Impressively so in fact.
That's about it. Now, I shall begin to dissect the impracticalities of the HTC One.
Let's start off with the aluminium unibody shell of the phone. Its exterior is attractive, and does indeed offer the feel of a truly high-end phone. It's stylish, feels solid, and... and... Yep. That's about it. It looks and feels good.
Massive advantage over the S4 there, clearly.
Now, shall we look at the cons? You cannot remove your battery, which is something I personally find myself needing to do quite often, you can't replace the back, should something happen to it(as is very likely, seeing that the body is aluminium, which has the tendency to get dented easily).
Possibly the biggest downside of an aluminium body though, is the exact thing that many have been praising it for - solidity. Upon impact, rather than absorbing damage, aluminium will allow the shock of the fall to just pass through and affect the insides of the phone. Polycarbonate, incidentally, will do the exact opposite.
On top of that, aluminium can get both very hot and very cold, naturally. There is nothing at all practical about having an aluminium chassis.
I much prefer having a polycarbonate phone, such as the S4, and enjoy the practicality of such a design.
I've covered the above in far more detail than I intended, so will make the rest brief. The S4 obviously has the better camera, which also sports dozens of features to tinker with, and excellent video recording(even though the latter is also prominent on the HTC One).
Another thing I wanted to address about the S4, was the sky-high amount of features it provides. Air-gesture, air-wave, S-this, S-that.
People write most of these things off as gimmicks and unnecessary, but I beg to differ. They add a new side to the phone, more areas to explore and options to consider. Yes, Touchwiz is quite heavy, perhaps even unnecessarily so, but I enjoy the vast amount of features put on the table by Samsung. They are the driving force of Android, and will rightfully remain so for a long time to come.