42" OLED would be a very distinct upgrade in terms of colours and black levels, and usually motion clarity. You either want to be going OLED, or at least something with a decent local dimming array these days, and unfortunately 40-43" TVs have got a bit of a bum deal in terms of development the last 5 years, partially because mainstream has gone to 55". The OLEDs are by far the most up to date and best TVs in this size, partially because development on the LEDs in this size kinda dwindled, unfortunately, whilst OLEDs only just came to this size range.
Just swapped from a temporary QLED set I was using, to an LG C3 OLED, in the bedroom, and everything about it is a step up in refinement and punch, even down to a noticeable step up in the processing power available for smart tv apps.
You have unfortunately missed Black Friday week's deals, but you can get the 42" OLEDs for less than a grand, with a 5/6 year warranty, if you keep an eye out. I got lucky and paid 699 for mine; and that was an LG C3, so probably the best you can get in this size; there are other more midrange sets that are typically cheaper.
The ONLY reason not to go OLED in this size now, is if you need to leave it on static images, banners etc for long periods of time repeatedly, albeit with mixed content and a bit of consideration, modern OLEDs are fairly hardy now. The 65" C1 in my lounge is now several years in, with a lot of gaming done on it, and no burn in, but it does get mixed content usage, even if lots of hours are spent in a duration on a specific game.
Depending on the size of your room, you often quickly get used to 48/55" as well, for what its worth!
