according to pcmag, black levels on the best leds are now better that plasma, to wit:
Historically, plasma HDTVs have produced the best black levels, specifically the now-defunct Pioneer Kuro HDTV brand. The Kuro's screen got so satisfyingly dark that it remained a popular HDTV for enthusiasts long after Pioneer stopped making the sets. The domination of plasma in this field, however, is over. Our current Editors' Choice HDTV, the LED-based LG Infinia 47LW5600 (Best Deal: $1,188.00 at TriState Camera), puts out only 0.01 cd/m2, the best level we can measure. That any LED-backlit LCD can get that dark shows how far the technology has come.
that said, i believe plasma still does certain things better (viewing angle, motion blur) and is a little cheaper than led; someone may well prefer one technology over the other.
White levels don't matter quite as much as black levels, because it's more difficult for screens to show fine details in shadows and easier to crank out very bright whites with backlighting, but they can still matter. At this, LED backlighting again triumphs. The Panasonic TC-L42E30 Best Deal: %displayPrice% at %seller%reaches a staggering 473.50 cd/m2 white levels with modest 0.04 cd/m2 black levels. It completely (and literally) outshines the Panasonic TC-P50ST30, its plasma HDTV cousin that puts out only 107 cd/m2 peak white while offering a slightly better 0.03 cd/m2 black level.
