Gaming monitors tend to be 60Hz, 144Hz or 240Hz and – again – GPU plays a large part as the refresh rate’s backbone. They work best in high-spec tandem.
If screen tearing (when your monitor shows information from multiple frames in a single screen) is the disease, FreeSync and G-SYNC are the cures.
Most new gaming monitors come with one or the other, so it is worth keeping an eye out. AMD FreeSync adds no extra cost to the base price of the monitor (but is only compatible with AMD graphics cards) and NVIDIA G-SYNC costs more but performs better (yet again only compatible with NVIDIA cards).
TN (twisted nematic) and IPS (in-plane switching) technology rule the roost and IPS is generally better, to put it simply. IPS panels boast better viewing angles, vibrancy and more accurate colour reproduction overall. Nonetheless, panel technology is rarely viewed to be as important as the aforementioned specifications.
This is one of the only times a lower number is better, spec-wise. Pixel response time is measured in milliseconds (ms) and is important for smooth, non-blurred camera movement. A 1ms response time is the best available (but the difference between 1ms and 4-6ms is hardly noticeable).