[Galaxy S 4 General] puremind:
Overclocked processor, contrasted, slightly bigger screen, removable storage and battery, high MP camera, extra sensory features vs.

Boomsound, stero speakers, microphone, screen brightness color accuracy and pixel density, fast, low light camera and premium feel

Other advantages on either side will be subjective (Sense vs. TouchWizz, Blinkfeed, Camera Software...)

I see many differences vs. last year (I myself did not chooce the One X for several reasons):

One X design was more premium than S3's (choice of materials) but the difference was less visible. The S3 design was sold well (like a stone in your hand, close to nature)

The One X has horrible lags when you tried it in the shops (even though later though development it got better performance, especially for games

Initially battery life was judged to be inferior 8even though later it greatly improved)

Process performance and battery life and the main two criteria when buying a new phone

A very long time I haven't seen any game changer in the market (the last one was the galaxy s2 two and a half years ago) and until there will be flexible devices or totally unbreakable screens.

The power button doubles as an IR emitter for the remote control, so the top placement is optimal. The speaker grille issue has been fixed everything completely flux now (see HTC Serial Thread, which tracks quality issues by production data and production location, it is very interesting to see how well HTC has reacted).

Also think about the antenna design.

Yes, it is not everything, which is why the HTC One is a game changer. Previously there was no phone that quite rivaled the galaxy devices in terms of quality of the components and now there is one that also has been widely acclaimed for its design and looks.

---------- Post added at 10:09 PM ---------- Previous post was at 10:01 PM ----------

Processor

Exynos is not better than the S600, it has more issues than the s600 as it has unfinished drivers (just read the S4 forum - if AndreiLux says that, I believe him, he is one of the most respected Samsung developers here. Whether overcloked or not the S600 is still the best technology right now. That's the only point I was making.

Camera

The blind test on Phonearena was done before the Software update. You can see how things compare here:

http://xdaforums.com/showpost.php?p=40705188&postcount=49

Microphone

I had three devices, one from early Match batches, and two from April batches. No microphone issues. It still remains the best technology. There is a reason Nokia is suing for its use. :)

---------- Post added at 10:17 PM ---------- Previous post was at 10:09 PM ----------

Come on guys we are now fighting over winning 3 seconds for the unlikely event your phone will freeze! That's not what you need a replaceable battery for!

---------- Post added at 10:28 PM ---------- Previous post was at 10:17 PM ----------

You make some very valid points below and I can tell you have used both devices. These points have been fixed or will be fixed through custom ROM's.

You can overclock the processor to S4 level

You can have 3 buttons - HTC logo is now used as an extra button (try HD Revolution 7.1 ROM)

LED notifications will be customizable (agree it is not as good as on S4)

You can download Swiftkey it is the best at predicting words and has entirely customizable layout. Personally I like the stock HTC One keyboard better than the S4's in terms of key layout, but the HTC one is annoying when you don't want to use a prediction, that's why I use Swiftkey now.