If it's shorthaul I prefer a window seat because it beats the 'entertainment' they show!!
If its a daytime longhaul flight I suppose I would lean towards a window seat, once again for the view and better entertainment by looking out the window!
If its a nighttime longhaul flight I may choose to have an aisle seat because then (being 6ft 2) you don't have to do the splits or climb over a couple of people just to go to the toilet!! But on the other hand, I don't mind a window to sleep against, so basically I'm un-decided!!!!!!