One of my students got a Samsung 17" LCD monitor and loves it. You can't go wrong there. In terms of bang-for-the-buck, Dell is still probably your best deal. Right now, on their web site, Dell prices are:

18": $539 (1280x1024)
19": $674 (1280x1024)
20": $899 (1600x1200)

We've bought a bunch of these Dell's in the office, and everybody loves them.