Thanks for your advice Sony is best brand no doubt but I have not enough money to spend Sony@asokan & @sach1979 bros, why you're looking for 4K TV? There isn't any 4K channel available, chances in near future is also bleak.
But if you seriously want to have, go for Sony only. It's lifetime asset. 55" starts at 90K in Amazon.
The model I bought 4 years ago (55X8500B at 2.15), costs almost half now (55X8500F at 1.2). Also my TV isn't android, latest model is.
The 4K UHD is mainly used for Netflix and YouTube
My purpose is both 4K content and full HD so I want to expect 4K UHD TV