It seems that in the next few years (before OLED TV prices hopefully drop to a comparable level to LCDs), people wanting to buy a premium TV will have two options: 4K LCDs or FHD OLED TVs. 4K resolutions usually means 3840 × 2160 (although some offer different resolutions) - or about 4 times the pixels of FHD resolution, hence the 4K name.
Obviously this makes sense. The higher pixel density means smoother images. But does it really make sense? There are two main issues here: suitable content and whether you can actually tell the difference.
According to DisplayMate, if your TV is smaller than 80" or so in size, and you are watching from a normal distance (i.e. not really close), it is simply impossible to view a single pixel in a Full-HD TV (your FHD TV is already a "Retina Display" if you want). This means that you won't actually perceive the difference between 4K and FHD in a 55" TV in your living room. So while 4K may be relevant for the cinema or huge screens, it won't be any good at home. Many reviewers claim that the images look better - perhaps they are looking up close or perhaps this is just wishful thinking?
Another important issue is the content. Currently there is very little (if any) 4K content available. Some manufactures are starting to produce 4K cameras (it is rumored that the Galaxy Note 3 will include a 4K video mode), but this is just the beginning. It's likely that 4K's fate will be like the fate of the 3D TV - very little content as it is not very attractive to begin with, even though most TVs will adopt the technolog. In addition, 4K content will quadruple the storage requirements which is annoying - you'll need more discs, a larger disk and a larger dropbox account. Is that just another consumerism conspiracy, trying to get us to upgrade our hardware to accommodate for content quality we cannot actually perceive?
Of course 4K TV makers say that their TVs can upscale FHD content to 4K. Using smart algorithms it may be possible to make a FHD image look somewhat better in 4K. But as we said before you will not be able to spot the difference anyway at home, so what's the point actually of all this?
The benefits of OLED TVs on the other hand are crystal clear - like the image quality of those TVs. Better contrast (deeper blacks), fast refresh rate, great color gamut, new form factors and eventually the technology will enable flexible displays and cheap production via printing as well. I think OLEDs win hands down over 4K. I'm not objective though, am I?
Of course it is highly likely that we'll soon see 4K OLEDs enter the market. This will render this entire debate moot. But still I think people should understand what 4K really means and whether it makes sense for them.