The AT&T HTC One X as well as the Verizon Galaxy S 3 will likely share the same audio hub included with the Krait SoC.
It this case, one could expect very similar, if not identical, sound from these variants of the respective devices.
As for the international version of the Galaxy S 3, it will be very interesting to see how the Wolfson audio hub compares to that of the Verizon version.
The audio hub in the AT&T HTC One X has been reported to be quite good. It will be interesting to see if Verizon indeed uses the same audio hub as the AT&T HTC One X for the Galaxy S 3, and whether the implementation of the audio varies or they are very similar. Samsung really screwed the audio with Galaxy S and variants. Thankfully, Supercurio came to the rescue!
As for the pentile display issue: this is really a matter of preference more than anything. I keep hearing both extremes of the issue as well as some more neutral positions on the matter. Personally, I have seen the HTC One X display. IMO, it is the best display out there, and beats the Galaxy Nexus and the LG Spectrum display easily. Also, IMO, the pentile sub-pixel arrangement on the Galaxy Note as well as the Galaxy Nexus both distract me a lot. Many people may not notice. I personally can't stand it. YMMV.
The HTC One X provides more realistic whites, RGB arrangement, excellent viewing angles, all while maintaining a high contrast ratio, nearly 1300/1. Also, I don't care what anybody says, SAMOLED nor SAMOLED+ does NOT have a an infinite contrast ratio. Just display a black image at night, and you will see the display. My guess is that the contrast ratio is well under 50,000/1 (excellent in any right, just not infinite.)
Regarding the colors of SAMOLED, they are absolutely over-saturated. This can be fixed by applying a color profile to images that you want to view in order to match the color space of the phone. When this is done, then photos look stunning on SAMOLED/SAMOLED+ displays. Additionally, some ROMs allow you to adjust the RGB values, which allows you to get very close to matching the sRGB color space natively, so most content will display as expected. When this is done, images will have natural and excellent color. The end user is better off with an IPS LCD, which will have far more accurate out-of-the-box colors than SAMOLED.
There should be other considerations if deciding between these devices. The AT&T HTC One X does not have an unlocked bootloader. The device may not get S-OFF (hopefully will at least get unlocked bootloader, though.) Both the international and Verizon Galaxy S 3 will likely have a great development following.
Ultimately, if you are a Verizon or AT&T customer and it turns out the audio is the same on each respective device, then the choice may come down many other factors. I'm on Verizon, but I almost want to buy an HTC One X off-contract, just because I think it is the nicest phone out there (my wallet won't let me, though.)