My preference would be the upper deck of the 747 - but that's very subjective. Depends on what you want to do on board. Seats are equally good, although the Austrian solo window seat gives you a bit more privacy, and space to store your belongings while working. Food on OS is typically much better than on LH (including superb Viennese coffees). LH has the advantage of on-board wifi (not available on OS) and the 747-800 is the sexiest aircraft around...