LG 47LH90 or Samsung UN46C6800?

I don't think you'll be disappointed. The LH90 is one of those TVs that after I'm done calibrating it I just sit back in amazement of how good it is.

If they are calibrated correctly, yes.

comparing LCD to plasma is not a fair game to judge black level.
Let me share with you what i summarize from the link (chart).
ignore the plasma section.
compare samsung B8000 and LG LH90 - samsung better right?
now what will the answer be comparing C6800 and LG LH90 - will C6800 be better or equal?
and also i personally find new LG 55LH90 is one of the best 55" LCD.

I remember looking at that chart and wondering the same thing at the time...WTF? The LH90 definitely has better blacks than the Samsung 860, from the time I had it in house I would compare it more to the Panasonic V10 for black levels if I had to compare it to a plasma.

Per CNet:
"In fact the LG's blacks were nearly indistinguishable during dark scenes from those of the Samsung B750, A950, and B7000 LCDs, and not quite as deep as those of the Sony XBR8, the Panasonic V10, and the Pioneer--but again the differences were subtle, even in a dark room in side-by-side comparisons."