From reading the model numbers one could easily infer that the 50" and the 42" are Panasonic sets, but what about the 56"? I don't think we should all have to search to figure out which make these are.
For the record, they are all Panasonic sets. The first two are Plasma sets, and the last one is Panasonic's LIFI projection set. They aren't even comparable IMO. There is a reason that Projection sets cost less, they are bulkier and have worse viewing angles than Plasmas, and more than likely worse contrast ratios. I would get the 50" Plasma set.