Not much to add from the previous posts they are pretty accurate. I don't own a HTC One X but here is a review comparing the iPhone5 vs HTC One X. Spec wise they are pretty close the S4 is on par with the A6 and with the T3. The T3 will only outperform the other two with CPU intensive apps like moves in HD and games.
HTC One X vs. the iPhone 5
We know how nice the screen on the One X is, and it's pretty universally accepted that it is the best the industry has to offer.