The reason the UltraSharp is so much more is because it is an IPS panel monitor. IPS panels have wider viewing angles. If you have an LCD panel right now, most likely it's a TN panel monitor. TN panels are known for their poor viewing angles but much cheaper to produce than IPS panels. The other three you listed are TN panel monitors as far as I can tell.
All of the choices minus the IPS monitor are generally the same. The poorest choice might be the first monitor (G2410) since it's the only one with no HDMI input. All three do support full-HD, though. So it's pretty much down to the second Dell and the Acer. I'm not a find of either brands, so I wouldn't want either of them. Try looking around for a Samsung or ASUS monitor instead.