The first thing I can say is that compared to an old 14" CRT
anything you buy will be vastly superior.
Personally, I would get a 19" CRT over a 15" TFT any day. You will find that the CRT will support a greater range of resolutions and as Robo says above, will have a far better response time for gaming.
The downside of a 19" CRT is size - it will be much, much larger than the 15" LCD.
The LCD will generally be sharper (at it's default resolution) than the CRT. Some people [me
] find an LCD too sharp and prefer old-fashioned CRTs.
The best way to decide between the two is to go to your local computer shop and get them to show you both screens side-by-side. Only that way will you be able to decide which is best
for you.