I was a hold out for CRTs for many years; I had an old UNIX workstation CRT. I'd bought it for $25 from a computer garage sale because the company had switched to Windows desktops from the workstations, and these weren't plug-and-play with PC graphics cards. It was big and beautiful for the time, and remained beautiful for a while beyond when LCD monitors started coming along. But, eventually, LCD surpassed that (very nice, originally very expensive) professional CRT. My current 4k LCD display on my laptop is miles away from even the best CRTs. No flicker, no ghosting, and extremely precise color adjustment capability, make even mid-range LCDs a better looking display than the best CRTs of the past.
Factor in weight (that big old workstation monitor weighed something like 75 pounds, and I hurt my back bringing it down the stairs when I finally got rid of it) and LCD is a no-brainer improvement over CRT. I have no desire to go back to CRTs.
My only 4k device is my laptop, which is a Dell with a "TrueLife" display (it's also a touchscreen, which I wasn't looking for, but it came with the lappy mode I wanted, and I've grown to like it in a short time). I've been kinda on the look out for a super good deal on a 4k monitor, but haven't pulled the trigger on that yet...I'm leaning toward a Samsung, but I would guess the higher end Dell monitors are fine...I've always liked my Dell monitors in the past. I used to always buy Viewsonic, but my last Viewsonic monitor was garbage in nearly every regard, so I don't consider them anymore.
I'd second Dell for monitors. You can also get a 4K TV, but do your homework on 4:4:4 chroma, since not having this results in basically JPEG compression on the image, which results in things like red pixels around text making it blurry. Note also that the Vizio 2016 P series claims to do 4:4:4 chroma at 60hx at 4K over HDMI, and it connects at that rate, but the actual displayed image is 4:2:2 or 4:2:0 in the low-latency gaming mode. http://www.rtings.com/tv/reviews/by-usage/pc-monitor/best has a good list, but in general, if you want DisplayPort, you won't find it on a TV. There are also things like the Wasabi Mango, Seiki, LeTv, modded freesync firmwares, etc. I just wanted something that worked, and for gaming at 120hz@1080p on a 55" IPS screen, I'm not disappointed.
Going the other direction, the Acer Predator XB321HK is a 32" 16:9 (I'm not a fan of the ultra-wide stuff) 4K screen with great picture and GSync if you play games with Green Team's GPUs. It's over a grand and only does 60hz, but it's a big nice 4K panel and it's not a TV.
Lastly, you have things like the Dell P4317Q, which is targeted at stock traders. It's a 43" 4K screen for a relatively-affordable $1350 with a proper DisplayPort input. I nearly got this instead of my Vizio P55-C1 (which is the only IPS screen of all the 2016 Vizio P series), but I liked that the Vizio did 120hz, but I'm disappointed about the lack of real 4:4:4 chroma and the resultant blurry text. Still, if you want a huge desktop monitor, the Dell might be the way to go. The Philips BDM4350UC is about the same as the Dell, and has a lot of discussion here: https://hardforum.com/threads/philips-bdm4350uc-43-inch-4k-i...
Factor in weight (that big old workstation monitor weighed something like 75 pounds, and I hurt my back bringing it down the stairs when I finally got rid of it) and LCD is a no-brainer improvement over CRT. I have no desire to go back to CRTs.