I had (and still have) a Panasonic 42" plasma.
Always been happy with it, never a problem at any time, and I would go back to it in a flash.
It is 8 - 9 yo and lacked HDMI inputs and HD turner. Back then they were monitors only.

I bought a new 46" SONY 3D ("SMART (?)with glasses etc) for the technology leap (and another property we own).
Tenants moved in and had their own stuff about 6 months ago. I tried to (re)sell the SONY but no one pays your price as they want a bargain and the price of tech is still falling.
I finally gave in and put the SONY in the Panasonic pride of place a couple of weeks ago and connected up the new (SONY) blu ray 3D player up.

I watched the Panasonic for years.
I will tell you despite being pretty power hungry (so I've heard) and it appears to run a little hot (warm on top after 3 - 4 hours) and yes I know I've only been watching the 3D LED SONY a few weeks but I do prefer the plasma over the LED so far.
I have noticed the LED goes a little white on viewing from acute angles (say more that 45degrees, like walking past the screen) and the contrast just doesn't appear the same for my taste

If I was to buy another TV it would be the new Samsung plasma (the really thin and border-less screen) in about a 50" - 60".
I understand plasmas are not as green but they are better than the older ones for power consumption for the picture quality I expect.