Bro I recently took a TS 4k connection late last year. I have shared my review in the thread mentioned by
@Bapun Raz bro. I had done some research prior to taking the connection. The 4k stb PQ and AQ are better than the HD stb when connected to a 4k TV.
However the 4k stb has a major issue. The signal quality will always be between 0 - 40. Many TS technicians, including managers have tried to solve this issue over the past two months without any success whatsoever. They even tried replacing the stb, using a Super LNB etc. but nothing has worked. The issue remains. My understanding is that it may be an issue with the software optimization on the 4k stbs or it could be a hardware defect with the 4k stbs. No one knows for sure.
If you can live with this issue then consider the 4k stb otherwise go for the HD stb. The 4k stb costs almost three times more than the HD stb, so I feel this issue is unacceptable.