There isn't a better TV than the C1 at that price range is 50" is actually the main limiter.
Given how cheap the C1 is as well, I would not bother with the A1/B1 due to the aforementioned lack of HDMI 2.1 support and a lesser quality, lower refresh panel. The 120Hz panel is still useful even if you don't play game, as it allows 120Hz BFI for incredible motion.
Sony are having a torrid time as far as F/W is concerned currently including botched VRR support and the FALD system being nuked (HX90/900) in a recent firmware if you do use VRR/HDMI 2.1 functionality. A few other TV manufacturers use the same Mediatek chip as Sony including Panasonic. Models to look at: X90J, HX90, A90 (OLED).
Panasonic - go for if you can get their entry OLED at a cheap price, but LG probably gets the nod should gaming or HDMI 2.1 ever be a consideration down the line.
Samsung - decent sets if you can get a QNED display, but generally cost more than the equivalent OLED and should only real be a suggestion if you're hugely adverse to cumulative wear of OLEDs.
My actual suggestion would be to plump for the 55" C1 if you can given the relatively minimal increase in price.