Samsung but only for the higher end (8 & 9000 range), I think in the middle band (around £1k) Samsung fall a bit behind Sony/LG/Panasonic etc. as they drop too many of the features/processing that make the high end models so good.
I’m still waiting for OLED TVs to drop a bit but looks unlikely now LG is the only one making them 🙁
As for size, I went from a 40″ to 55″ last purchase (a couple of years ago) and you only really notice the difference for a couple of weeks, it just seems normal to me now. Only issue I did have was the TV stand overlapped the edges of my cabinet (and the TV weight was on the outer edges) so had to change the cabinet but if you’re wall mounting you won’t have that issue).