WE like B1 or B2. B1 doesn't have feet above and has the height, but B2 gives a better view of the screen itself (you are dead on centre). So we like both of these locations. For anyone with a fear of heights, I would choose B3. Also, my DS gets queasy on this ride and finds row 3 slightly better (I'm not sure why?)
If you are in section A or C, try to get seats located near section B (the middle block of seats)
ABC refers to the concourse (block of seats), 123 refers to the row, with 1 the highest and 3 the lowest.