I needed a new tv last xmas (my Panny Plasma went bang the week before xmas), it had 12 days left of it's 5yr warranty, so it went off for repair and they told me it would be back before xmas.
Needless to say it wasn't so boxing day I went out and bought a 48" Samsung 1080p lcd, that had great reviews.
I was VERY disappointed with the picture quality, compared to my plasma it was sh1te unless sat slap bang in the middle of the screen, then it was ok, but black was grey and it suffered with motion really bad, the picture quality was no better than my 7.5yr old Sony ccfl lcd tv (infact the sony is better because it doesn't suffer with motion judder and doesn't wash the colours out if you sit off centre).
So I returned it, and bought a Samsung 48" UHD instead, thinking that if I spent proper money on a top spec tv, then I would be happy.
Again the colours washed out if I moved away from centre of the screen, and on normal 1080p content the picture was nice, but still not a patch on the Panny Plasma. On 4k stuff (Amazon Prime and demo clips) it looked fantastic, but it didn't impress me enough to keep it, so it was also returned.
2 weeks later I was given the bad news, that my Plasma was beyond repair, so Panasonic replaced it with a brand new lcd tv (which also has a sh1te picture).
So I started looking at OLED, the black on them is better than my Panny Plasma could do, and the viewing angle is crazy, you can sit right at the side of the tv, to the point that you can only just see the screen itself and the picture is still crystal clear.
But for the time being, i'm going to wait it out with this Panny LCD, once there are defined 4k standards then I will move to OLED (it's pointless putting £1800 - £3000 into a highend tv set at the moment imo).
If this Panny were to die tomorrow, I would opt for 1 of the cheaper 4k lcd's (probably from LG) as a stop gap.