I bought 3 Samsung 51" plasmas within the last year or so and they are all amazing. 51F4500 AFXZA, 51F4500 BFXZA, 51F5300 BFXZA Absolutely zero regrets with any of them-- they produce the best pictures Ive ever seen.
As for the 4500 series, it doesnt matter if you get an A or a B rev, they are both simply incredible sets, at under $400, in my opinion they're the best bang for the buck in the history of television panels. The differences between the A and the B are just a few items in the menus. In my opinion they produce the most CRT-like picture available in a flat panel, and are the best gaming TVs you can buy for all consoles below the XBone and PS4 (though they are great for those as well, just not as well suited for them as the 5300s).
The full 1080p 51F5300 is spectacular for Blu-Rays, PC, and Full HD game consoles. Netflix Super HD and OTA HD also look great on it.
The larger pentile matrix F5300s are also fantastic, I just didnt have the right setup for larger than a 51".
The F8500 series, well, its one of, if not THE best TVs of all time.
Ive seen LG plasmas and they are very nice as well. We have a 60" at work in a meeting room and its full 1080p, looks great. Good bang for the buck.
Basically plasma beats LCD in almost every conceivable area of PQ. They are like giant, super thin CRTs (this is a good thing). They have that same "warm glow" and perfect viewing angle.
The only areas I can say that LCDs beat plasmas is the lack of line bleed (not a big deal with plasmas, but they all do it), and zero potential for burn in/uneven panel wear. I'll give them that. Oh yeah and they're great for tee tiny screens as well.
Long story short better get you one while you still can...