Hai: I always love the 'on location' photo books, especially if they make good use of it. Hai, Muboubi and the solo trading cards make for a very nice collection of Acchan's trip. However, some of the pics were a bit creepy, so it loses points for that.
Acchan: This is probably my favorite. Sunlight, beach, various cute and wacky shots too. It's a feel good photo book.
Maeda Atsuko: Definitely the least interesting the the trilogy. My fav shoots are the indoor ones where it shows what life with Acchan would be like.
Atsuko: Another really good one. I felt they could have made better use of NY, but the sheer amount of mature and sexy shots makes this an instant classic.
Bukiyou: I never really liked this one that much for two reasons. Too many out of focus shots + going for the obvious perv angle in a lot of pics, not unlike Hai. On the other hand, Paris looks good on Acchan and it still is a fun book. Hand-bra Acchan shocked the world, for better or worse.