Do not worry about the contrast ratio. It is simply the ratio of black to white at full brightness. Most monitors have MORE contrast than the user can even see!
Also, different manufacturers rate it differently, and the ones with the REALLY high numbers use something called dynamic contrast where they turn off some of the LED backlights to make black blacker to greatly increase the ratio.
yeah i heard about dynamic contrast and that its better but i can't really tell which monitor have dynamic contrast. but as far as i understand, fix me if i'm wrong, contrast ratio useful when i'm changing brightness right? but when i'm on default setting its doesn't matter?