I’ve reviewed some of these HDTVs personally (both LCD and Plasma). In general I prefer plasma for reproduction of moving images, color reproduction and black levels/contrast, but there are some LCD sets that are better than some plasma sets. Resolution (1920x1080 vs. 1366x768) really isn’t the most important measurement of a set (particularly at normal viewing distances), but all else being equal, a 1080p set is sharper than a 768p or 720p set.
I think the current “best” bang-for-the-buck and possibly the best set out there under $3K in the 50-inch size would be the new 1080p Panasonic plasmas. A little outside your price range but not much ($2600). Here’s a link:
http://www.bigpicturebigsound.com/panasonic-1080p-plasma-1139.shtml
I’ve set up and calibated one of these for a friend and was very impressed by the detail and color accuracy. No visible image retention and minimal reflectivity of the screen. This is the one I would get if I were buying today.
-CB