It is fair to note that the many of our portraits are shot in landscape format (wider than they are tall). Generally in a sitting we will shoot both landscape and portrait format; however for many modern applications the landscape format will find more use. Shooting wide often allows an image to be cropped in a variety of aspect ratios.
Maybe it is through watching too many films but having the opportunity to place the image within some neutral space seems to allow the image to ‘breathe’ a little more freely.
Ultimately the style of the session will be decided by the likely end use of the images