The most fundamental aspect of a monitor, and likely the most important because it affects nearly every facet of the display other than sound, maybe. There are three main varieties of LCD monitors in use, with different characteristics. However, all of them have merit and the differences may not necessarily be night and day.
TN (twisted nematic): still the fastest panel type, so if you see a 360Hz monitor, it’s almost certainly TN. For the highest refresh rates and quickest response times, TN panels do not disappoint. On the downside, they still suffer from the narrowest viewing angles and least appealing color reproduction. Black levels and contrast are OK, though.
VA (vertical alignment): great all-rounders. Excellent contrast, respectable response time, good colors, and better viewing angles than TN. VA panels are somewhere in the middle and that’s why they’re so popular, particularly for bigger monitors and TVs. They have a slight tendency to suffer from ghosting, but improved technology has largely banished this flaw. Not as fast as TNs but definitely close.
IPS (in-plane switching): considered the most competent in terms of color performance and viewing angles. Response times and refresh rates are similar to VA, so slower than TN but still OK for most needs. The biggest advantage of IPS technology is color presentation, which is by far superior to the other two varieties of LCD, although IPS has a reputation for less than great contrast and black levels.
Learn more about panels types and take a closer look at IPS panels in particular.