Displays: HTC1 (Sprint), LG Optimus G (Sprint), and LG G2 (Verizon)

I know that the specs are less impressive for the Optimus G than for the others:

LG Optimus G: 1280x768 true HD IPS, 4.7" display, 318 ppi

LG G2: 1920x1080 true HD IPS, 5.2" display, 423 ppi

HTC One: 1920x1080super LCD3, 4.7" display, 468ppi

Yet I find the display on the Optimus G far superior to the G2 or the HTC--crisper, more detailed, sharper, and has more vibrant colors. There's a little fuzziness to the One and the LG which is not present on the Optimus G. Moreover, the white on the Optimus G is true white; the G2 is more yellowish and the One more yellow still.

I've been comparing these screens for weeks (and in the case of the Optimus G and the HTC One, for months), and my impressions haven't changed. But what could account for the (perceived) difference in quality, since the specs for the Optimus G display are clearly less impressive than for the other two?