CRTs are better, but a good LCD works too. My 16ms 17in LCD plays great, but the colors are a little off, and the contrast in Doom 3 makes it even harder to see. I hear ghosting is a problem in games. The lower the ms the better--at 16ms I don't see it. Contrast ratios need to be high(mine's 450:1 and too low).
If space is a comodity, LCD is the way to go (Plasma is much better).