4k TVs were way too overpriced a few years ago. But this year 4k TVs are starting to replace regular HDTVs. An increase in 4k content and the lower price point I think have really sped up this shift.
Whether you are buying it for yourself as the ultimate treat, or a family member, 4k TVs are a gift that will keep on giving for years to come.
I personally have always used Samsung and Sony TVs. I had a Samsung HDTV that lasted over 10 years before I sold it. Great picture and held up fantastically. However, LG has put out some very competitive models recently so you should definitely consider them as well. Most models come in a variety of sizes so you can select the size best for you after the link.
I realize that cheaper brands like Vizio and TCL are quite popular. But you get what you pay for. For many, paying 25% less is worth a lower quality contrast or clarity. The way I see it though, is that you will spend more time with your TV in the next 5 years than any other electronic (besides your phone), so I want it to be the best.