Depends on how much you want to spend. I just bought a dell S27 monitor because it's being phased out and incorporating HDMI instead of DVI-D. It was $250 on sale, IPS, amazing input lag, etc. However, it's only 1080p. The reason why I didn't go 1440p is because 4k monitors are finally coming out consistently and at lower and lower prices. I can deal with a lower res monitor now and will buy a 4k/5k monitor within the next couple years.