The Asus PB278Q has a resolution of 2560x1440 and Wide High Quality Definition and a PLS panel and a 5ms response time.
The two Dell monitors U2713HM and U2713H have the same panel and resolutions but the response time is higher and the U2713H is slated primarily for graphic design and photo editing work.
The Dell U2711 is more comparable to the Asus and if your looking for a gaming monitor then it would be between the U2711 from Dell and the Asus monitor. The Asus monitor is $50 cheaper so if money is a concern then you could go with the Asus
In some of the descriptions that I have read on all three of the Dell monitors it seems like they were made for professional work and not gaming. So I would go with the Asus monitor. Everyone says that the Dell's are great but it's all graphic designers and photo editors that are saying that.