I own both a New 2015 Samsung JS9000 and a 2014 Sony 65X900b. Both devices have strengths and weaknesses.
Upscaleing on the Sony seems to still be a little better than the Samsungs but it is very very close.
Color Vibrancy / Pop would probably go to Samsung now but not by allot.
Black levels are pretty close with the Samsung probably holding the edge slightly.
I love the new Samsung Smart Interface even though the last update messed it all up and Netflix is sill not working.
The 2014 Samsungs did not hold a candle to what the 2015 performance levels to me.
I would say if you are looking at the Sony 900b or 950b then you will be happy, anything less than I would not waste my time.
Samsungs I would stay with 2015 only models myself, the new SUHD line I know holds up to the Sony line.
The 2015 Sony models could change all of this if when they come out and are amazing
Just my thoughts and I hope it helps.
Now if ou can find a Samsung pf8500 Plasma then that would put a real kink into things as it is still a GREAT display that rivals all.
Current Sets: Sony XBR75X940C, Sony XBR75X940D, Samsung UN65KS9800, , UN55KS8500, UN49JS8500
Previous Sets: Sony XBR65X930D, XBR65X900B, XBR49X830C, Samsung KS8000, KU6500, JS9000, JU7090, JU6500, JU6400, HU9000, HU7250, PN64F8500, Vizio P65, LG 65EF9500, LG 55EC9300, Hisense 55H8C