I am extremely happy with my Panasonic plasma. Unfortunately I can't offer any empirical evidence as to why I prefer it to any other set that is available. Based on viewing experiences in the home of friends and family, I feel like my Panasonic offers a better picture.
My parents have a 40" Sony LCD. Picture is hard to judge because my dad keeps the tint heavy in the read.
A good friend has an Insignia 55" LCD that has a surprisingly good picture.
Another friend has a 55" Samsung plasma that has a picture I could be happy with.
I've also spent some time with Samsung and LG LCD sets (meh).
Again, this is strictly anecdotal nonsense. Get out there and look at a bunch of stuff. Take your favorite Blu-ray to a buddy's house and check out his set. You're getting ready to drop a fair sum of money on something you're going to be looking at every day. Don't shortchange yourself by not doing the legwork. Besides...it's fun!