Can I express a "no preference". The one on the left looks more Dellish (Latitude) and the one more HPish (Pavilion) though. To me, a laptop needs have a screen, touch pad, keyboard with num pad and function keys and then it's just really size/weight/battery ratios.
Isn't the one on the right an Ultranote chassis and the one on the left a Genesis V? I'd go for the latter... hoping you are asking to decide in addition of the Lafite' 15" to the family