Have you booked a seat for your 12 month old daughter, or is she sitting/sleeping in your lap?

I personally find the Swiss A340 seats to be more cramped than the LH 748 seats, so with a lap infant I would probably prefer the LH 748. With a seat, there's less privacy between the pairs of seats on the LH 748, so it's possible to see your daughter's face while both of you are wearing a seat belt.