The LG and Dell are very similar - both 3D monitors, same resolution. Dell slightly faster response spec. Both about the same price -$450. The Benq is LED, and response spec faster than either LG or Dell. It is 3d capable. And it can be had for about $328. It is also rotatable.
I would like to see them in a store - but sight unseen - specs only, I would choose the Benq.