We initially purchased a 50” Samsung UN50KU6300FXZA and tried that out for about a week (from a big box store). We really liked that TV, but we were having a problem with occasional audio skips on that TV so we ended up returning it and exchanging it for a Sony XBR-49X800D. I am not really sure that the Samsung had audio issues itself, it could have been something external (I ended up replacing a lot of cables and connectors as well).
Since I ended up trying out both TVs, I can contrast them to some extent. The Samsung is a very stylish TV and looks a bit more upscale than the Sony. The pedestal seems a bit more stable, although both of them, being center stands versus the more common feet on either end, worked well with my TV stand. The Sony, on the other hand, is amazingly thin for a 49-50” TV, more-so than the Samsung.
I tried the audio on both and I thought the built-in audio on the Samsung was a bit better, although for me it’s a moot point since I am using a Yamaha sound bar connected to digital audio out on the TV.
There was something very pleasing about the picture on the Samsung, although the contrast and colors seem a bit better on the Sony, given proper adjustment on both.
On the Samsung, when I had the motion smoothing and judder control features turned on, some broadcasts had a serious problem with the infamous soap opera effect and I found that, to avoid this and have a picture I liked I had to turn most of that stuff off. On the Sony, on the other hand, I am using some (not all) of those settings and I am not getting the soap opera effect like I did on the Samsung.
I liked the “smart” features, including the arrangement of the user interface, a bit better on the Samsung than on the Sony, it was a tad more intuitive (although the features were similar).
The Sony seems to have more settings for adjusting the picture and audio than the Samsung did, although I liked the interface for doing that better on the Samsung.
The Samsung remote is small, elegant and confusing. The Sony remote is more traditional and has a lot of buttons on it (the Samsung remote hardly had any).
Both TVs seem to work fine on my WiFi network and both were able to stream 4K content just fine (e.g. Netflix).
The Sony has 4 HDMI ports vs 3 on the Samsung.
The Sony TV uses an external brick on the power cord like a laptop (a big one), the Samsung has a normal power cord.
The cables on the Samsung all plugged in from the side (in the back, but parallel to the back of the TV), the Sony cables plug into the back perpendicular to it (I don’t hang my TV on the wall, it’s on a stand, but I think the Samsung would have worked better for hanging on the wall).
All in all, I don’t think you can go wrong with either set, they are both good TVs.