General things:
If you are looking for space saving and/or engery usage- go with a LCD.
If you play games or work on serious graphics- go with a CRT.
Other things to keep in mind-
- There are deals to be had if buying an 18" LCD monitor right now, as that product category is going away.
- Buying a monitor with a Sony Trinitron tube could be an issue, as they are discontinuing making the Trinitron tube (which means all other vendors who use that technology will either have to stock up or switch).
- Going forward (a year or so), the only true flat-tube monitor maker will be NEC-Mitsubishi; as they aren't going to do away with that category (yet).