Top end CRT displays have yet to be surpassed when it comes to response time, accurate colour rendition and brightness. Which is why you will still find them in 99% of all TV studios and film sets around the world. Pumping a HiDef signal through a studio Barco or Sony CRT creates a picture so sharp you could cut yourself on it. In fact there were a few HiDef CRT sets available in the States a few years back I believe. but I'm not sure if there are any about now. They weighed a ton and cost a fortune. From a technician's veiwpoint, it will be a few years yet, before LCD, OLED systems will be as good as current state-of-the-art CRT displays, although when the new laser screens hit Europe, I think there will be something of a revolution. Try to Google the Mitsubishi LaserVue L65A90, or even the 75" version if you have £6000 to burn.
However, picture quality is not just a matter of how many pixels the display is capable of.
There are two main HD resolutions in use today by HD broadcasters and other sources: 1080i and 720p. One is not necessarily better than the other; 1080i has more lines and pixels, but 720p is a progressive-scan format that should deliver a smoother image that stays sharper during motion. Another format is 1080p, so called "full HD" which combines the superior resolution of 1080i with the progressive-scan smoothness of 720p. Due to the huge bandwidth involved in transmission of this format, it is usually only available via BluRay, although with the advent of fibre home networks and faster electronics, it may someday be available through your "cable" TV supplier.