If you're alone, personally I would go for the A333 because you can take a seat in the center section and not worry about anyone climbing over you. The 77W has 3 seats in the center section, so unless you get lucky and your seatmates are together then you run the risk of being climbed over. In the window side you're guaranteed to be climbed over or have to climb over someone.

If you're with traveling together with someone, then both are pretty much the same, especially if choosing the seats on the window sides. The 77W may be marginally quieter than the A333 but not by a huge margin.