LCD, absolutely. Like slyno1324, I find the lack of flicker makes them a lot easier to look at over a long period of time. I always turn the brightness on mine down as far as I can while keep tweaking the contrast until I get the LCD as dull as possible with acceptable colour reproduction. I find this is the most comfortable setup to look at for long periods of time, but if you’re doing a lot of graphic design/photo work it won’t be great because you’ll loose some colour fidelity. If you’re mostly coding (like me) this setup works very well.
If you can afford it, get two or whatever monitor you choose, the productivity gains from two monitors are huge. LCD’s are good for dual head systems because you can place them right next to each other without interfering with each other.
I found the combination of flickering CRTs and fourescent lighting (which are also flickering) results in a lot of eye strain. Since I switched to LCD, it’s mostly gone, and I haven’t looked back.