The U2410 will probably give you the best quality image, but at 6ms response time it is a little on the slower end for gaming monitors. The U2412M is 8ms response, which for most is beyond the acceptable limits for gaming. I personally try to shoot for no higher than 5ms, but 6ms should be ok.
16:10 is great for gaming. I love the extra vertical pixels as it helps the image to not feel as ... squashed, I guess is the word I'm looking for. I tend to go for Eyefinity setups, so I sacrifice a bit in the individual monitor in order to get the full surround effect. Single monitor though, I'd go for the Dell.
The Dell should give you a better experience than the Acer or Asus will, but obviously at a higher price.