Manufacturers don't often advertise this, but for gamers...
The MOST important thing is "input lag"
Pretty much all LCD's have ungodly high input lag numbers...
Manufacturers don't advertise input lag, because next to those fast response time numbers it looks terrible.
Though for gaming, an input lag of less than 50ms is pretty good.
I would say ideally, I would like an input lag of about 16.66ms or less...
(This would be on par with a 60Hz refresh rate. At 60Hz a monitor refreshes the image on the screen every 16.666ms)
Not sure if they make any LCD monitors with input lags that low.
The only way to find out really is to find a review of the monitor where they measure the input lag timings.
If you want a monitor with good color quality, fast response time, and no ghosting...
What you'll want to be looking for are an S-PVA, P-MVA/MVA, S-IPS panel with low input lag.
If you want a cheap/affordable gaming monitor that's fast, you'll want a TN panel with low input lag.
Response time doesn't really matter as long as it's below 16.66ms for a 60Hz monitor, or 8.33ms for a 120Hz monitor.
120Hz monitors are considered good these days because they can be used for 3d gaming, and they are easier on the eyes than a 60Hz monitor, but in reality they aren't much better for everyday usage than a 60Hz monitor.
They have no advantage over a 60Hz monitor in movies in terms of overall input to the brain.
In games, they may make things slightly smoother, but it's not all that noticeable unless you're one of the people that actually look for the differences.
For the most part, read reviews, check input lag.
Response time isn't as important as monitor manufacturing companies like to make you think it is.
I had an 8ms GTG MVA panel monitor that was an amazing monitor for gaming and it was also great for watching movies.
(You would have a hard time finding one for sale now.)
But it's an L2410NM
A 24" 1920x1200 monitor from Westinghouse with 176 176 viewing angles .282 pixel pitch and a fairly low input lag.
Good enough to play console games, FPS's like Half Life 2 and Crysis, and pretty much anything else. (I played all those games on it very well.)
I never had a problem with it.
Oh one more thing I forgot to mention.
Higher quality monitors have low pixel pitches, giving them more PPI.
(Pixels per inch) monitors with very low PPI have clearer text and overall better color contrast/reproduction.
I don't keep up with monitors enough to offer specific recommendations, but these are things you should be looking out for.
(Ways to tell a TN panel from a non-TN panel.)
TN panels usually have very low response times, are cheap, and have viewing angles of 170 170 or less.
Non-TN panles are usually more expensive, have response times of 6-12ms and have viewing angels of 176 176 or higher.
*Note, sometimes companies apply a special coating to their TN panel monitors increasing their "viewing" angles up to 176 176 or higher, but they are still TN panels regardless of this "special coating" and in reality it doesn't really help much and doesn't add anything to their overall quality.
Bleh, I think I covered most everything... :\
I'm probably forgetting some important key points, but I'm sure someone else will make specific recommendations and point out things I forgot to mention.
EDIT: Forgot to mention contrast ratio.
The best contrast ratio is 1000:1 STATIC
Ignore the dynamic numbers and active numbers manufacturers advertise.
Look for reviews where they check the STATIC contrast ratio.
You want it to be 1000:1 or 900+:1
GOOD monitors are 900+:1
realistically it's hard to find monitors that live up to the 1000:1 specification but a few are out there.
Manufacturers have fancy ways of beefing up their contrast ratio numbers with their "dynamic" or "active" contrast ratio technology, but really the only important thing is that the STATIC contrast ratio be as close to 1000:1 as possible.
What the heck I'll make some suggestions...
Stay away from Hanns G and Acer if you want a quality monitor.
Those are budget monitor brands, and they usually end up with some sort of problem...
Bad color distortion, crappy angles, light bleed, dead pixels, funky wack stuff...
Samsung and Asus are good brands for an affordable decent quality monitor for gaming.
I recommend one of those guys.
They have the size you're looking for.
One is 1920x1200, they both have low pixel pitches and their static contrast ratio is listed as 1000:1 so it's probably somewhat close?
I didn't check reviews, but I've seen these Asus monitors in person and they're pretty nice generally.