The highest contrast ratio of the Acer 42HLAbid is 100000000:1. That's over twenty times the contrast ratio of the most common dynamic contrast ratio of 5000000:1.
A 100000000:1 dynamic contrast ratio is actually the best contrast ratio amongst all PC displays of this type and age.
Amongst comparable types of PC monitor the worst contrast ratio is Mega Contrast.
There are a number of other flatpanel monitors that have a 100000000:1 dynamic contrast ratio currently available that you might also want to consider including the Acer H277HU which has a better Rating.