nice forum.. good discussions.. below my thoughts:
Rule#1: Always consider the biggest size possible in your budget.
Rule#2: Don't go for 4K, unless you are planning something above 60" panel.
I've gone through lots of research recently before getting Samsung 48H6400 for 59K (from ebay india - with 1 year dealer warranty). This is one of the good tv with Smart, 3D, 120Hz panel, with great black levels, good deal for that price range. You can get 55H6400 for 84K or so. And above all, H6400 series is DIRECT LED (not edge); resulting great screen uniformity and black level control. Once you see this TV, You will laugh on any IPS panel (LG/ Sony) greyish blacks.
Samsung 8000 series and Sony W900B and above series are always better than H6400.
I always opt for a 55" 6400 series on top of a 46" F8000 for the same price! Believe me 42"TV look really small in a matter of time! - you'll start looking to upgrade to 50 or above.