The One X's display is, without a hint of hyperbole, the best I've ever seen on a phone. Full stop. Seriously, I'm struggling to find fault with it in any way: it's got a near-perfect 180 degree viewing angle and perhaps the most accurate color reproduction and color temperature available. At 720p, it falls well into "retina" territory where the individual pixels become invisible to the naked eye. It also lacks the infamous pentile subpixel arrangement commonly employed on high-resolution AMOLEDs like that found on the One S, and it runs circles around the Galaxy Nexus's 4.65-inch Super AMOLED for overall quality.
Historically, one of the big reasons manufacturers have chosen AMOLED over LCD is because AMOLED is thinner — it's self-illuminating, so there's no need for an external lighting arrangement. Considering that the One X packs its SLCD into an 8.9mm shell, though, that concern has all but evaporated (compare it to the 720p Rezound, for instance, at a beefy 13.7mm).