You have three different panel types to choose from.
TN panel, fastest response but viewing angles are limited:
Asus ROG PG278Q - Note that this monitor has only a single video input (Displayport)
IPS panel (including PLS and AHVA), best colour and viewing angles but has a glow in the corners that can frustrate some users:
Dell U2713HM
Asus PB278Q
AMVA panel, best black levels and good colour and viewing angles:
BenQ BL3200PT (actually 32 inches at 2560x1440)
For reviews on any of these monitors or on the different panel types, visit www.tftcentral.co.uk.
These are all 2560x1440 monitors.
The pixel density of a 24 inch at 1920x1080 is good. This is pretty much the standard people have come to expect.
Anything larger at 1920x1080 tends to look grainy.
A 27 inch monitor at 2560x1440 has superb pixel density.
A 32 inch monitor at 2560x1440 has the same pixel density of a 24 inch monitor at 1920x1080, which is still quite good.