The one I use is 49 inch Sanyo Nxt series TV. Sanyo is now a sub brand of Panasonic and hence there's peace of mind as the hardware and service is managed by Panasonic themselves. The screen is good too, has IPS display. Once con I found is the hue cannot be adjusted unless you're in NTSC mode and the skin tone is a bit off. Picture quality is very good and the display is very bright too.
Sound is average, Now I have added a yamaha home theater to it and that fulfils my requirement. One thing to note is that It doesn't return 5.1 audio through arc only stereo.
Coming to smart features, not a big fan of android Tvs. I would suggest to go with a normal tv and get android boxes like mi box or Firestick. I use chrome cast and it is good. I doubt apps in the TV will support full resolution especially in 4K.with things like chrome cast, we not only save money but also can ensure of the contents played. Also chrome casts can be connected directly to the Home theater through HDMI in case the TV's sound out put is not good. Not sure of other TVs but Sanyo has Audio only mode where the Tv turns off but the audio keeps working. Also, not many brands have IPS in their low range. IPS is good.
This is the link to the TV I use.
Sanyo NXT XT-49S7200F.
If your viewing distance is less than 10 feet and want 50+ inch TV, go for 4K. Speaking about 4k, please pay more and go with 4K HDRs of Panasonic, LG, Samsung, sony, Toshiba or nothing less. Forget about Sanyo or MI because, 4K panels of budget TV will not have proper HDR although they mention it.
The experience of difference between 4k and 4k HDR is more big than the difference between 1080P and 4k.
In a nutshell, if budget permits go with 4k HDRs (dolby vision will be very good) of well known brands. Or spend less and buy TVs like Sanyo, TCL or IFFalcon.