I have a TCL 55" 4K 6 series. I did lots of research and didn't see many complaints of them not working for long. They actually had lots of reviews praising them for being long lasting. The big issue with them has been vertical banding. And it can be bad in some tv's. Mine has a minor amount of it, and it doesn't bother me at all. I watch a lot of hockey, and the banding isn't making the ice off color that I notice.
Extremely happy with my purchase and it's nearly a year old. I picked TCL because of the mixed reviews I read for Samsung, Sony's, LG's, Toshiba's and Hisense's. All had serious issues occur within two years of ownership. I didn't see that with TCL.
I'm really glad I didn't drop another $600-1000 onto QLED's or something because I know a few people who wish they hadn't. If you're going to drop over $2k go for OLED.
If you're looking for the best tv in a lower price range, TCL is tops. Series 4 is the most popular and the price is a steal for a 55", but I went with the 6 series and am happy I did. TCL is better for gaming, but has very nice resolution and presentation of movies, as well as sports and tv. Not a great tv to view from the side, but if intended for a bedroom, yup - prolly best choice. If for living room, maybe consider a curved TV.
Anyway, happy shopping and I hope you get what fits your needs the best.