NEC and eizo's pro lines are the gold standard in monitors. the panel models often have the same part numbers as other products, but: 1) they implement the highest level of display correction 2) best warranty service 3) they buy the highest grade panels from the panel manufacturers.
apple is only a little behind on 2 and 3, but their performance on 1 leaves much to be desired. also, their proprietary electronics are a PITA to work around.
ps, metal vs plastic exterior chassis has absolutely nothing to do with panel quality.