personally i think get the a43sv if u need an i7 14" lappy or hate optimus. Get the u41sv if u want long battery life or maybe lightweight(relative to the other two models) and get n43sl for any other reasons(even though not exactly proven to have better cooling and build quality but expected to have )

max around 4 hours with light browsing at lowest brightness, i would say its's pretty good for a quad core. But i suggest you get u41sv then if battery is your main concern.