the best mid-level brand in all of them is LG .... LG by far has really impressed me over the years, with their software, designs and costs.. i hate samsung, the only reason people go for samsung is typical market share and hype... sony is underestimated, but has never impressed me, regarding tvs i.e
TCL my friend is using, its a normal led, not even fullHD. but it looks ok. changhong isnt that good, software is mediocre and slow mostly. ecostar is a little better then haier/orient etc, but not very.
at the end of the day, you need to see what suits you, in what price etc. LG 4k quality is top notch..
just a food for thought, there are not many 4k contents for you to stream properly. online content is limited, movies as well.. there are only mostly demos and trailers going on about. full 4k content isnt yet available anywhere here in pak.