if you want flat panel, obviously Plasma and LCD are your only two available options.
if you don't have to have flat, go rear projection. the price-per-inch of flat panel plasma or lcd is significantly higher than any of the top rear projection technologies (although they have dropped quite a bit as time has gone on).
i had to go rear projection because i wanted 70" and didn't have $30,000+ dollars laying around for a flat panel. regardless, my calibrated sony kds-r70xbr2 blows away the picture on any television out there period, except for, some might say, the pioneer elite kuro 1080p plasma 50" or smaller (pixels denser and packed closer together). i don't dig the glare of the glass screen, and i prefer the image on my set.
sony's rear projection technology is a version of LCD called LCoS (liquid crystal on silicon), and their version of that is called SXRD (JVC's is called DiLA). out of LCD, DLP and LCoS, my personal preference is LCoS. smoother picture, more natural colors, better black level, no rainbows, no screen door effect, no silk screen effect, wide viewing angle, yadda yadda.
sony has bailed out of the rear projection television market, so they will never improve on the model i own. unfortunately it only came in a 60" and 70" version. a lower level successor television came out called the A3000, which is also supposed to be excellent, i think it might be available in as small as 50". i'd check that out if you can still find them.
even a rear projection LCD is going to be significantly less expensive than a flat panel LCD if you decide to go that route. if you don't need to pay a premium for flat panel, why would you?