What do you want to do becomes the question. They are all wide-gamut screens, and two of them are IPS. Depending on which version of the NEC you get it can come with the Spectraview kit which is a hardware calibrator tied to the screen which will help get accurate colours for doing colour critical work.
I can recommend the HP over the Dell as I've owned both and sent the Dell back within days, the HP is the 24" monitor I've had the longest (there's a few of us on here who've had multiple monitors and sent them back trying to find a decent one).