if number of pixels and clarity are the only things a buyer cares about
then it could be a true statement that a 4K TV is better than any 1080 set
but there are other things to consider within a given budget that could make 1080 a better buy
[video=youtube;ggiU5KQsB3I]http://www.youtube.com/watch?v=ggiU5KQsB3I[/video]
one hopes you can see the difference on whatever you are using.....it's rather obvious on a Retina screen. You should be able to see the difference just on the splash screen in the video above.
There is no justification to buy a 1080p at this tech point in time. In addition 4k upscales 1080p content rather nicely.