I voted for most of the books, but I think that if I had to chose three they would be the Epic Level Handbook, Al Qadim, and Oriental Advenures.
I was not very pleased with the ELH. The epic spell system seemed to be not terribly effective, as opposed to getting more spell slots for metamagic feats. Also, every other type of magic -- divine, arcane, and psionic -- are based on levels. So, a revision of the magic system might work.
Additionally, i did not care for some of the feats, and I don't care how high your skill levels are, if you are playing a human, your character is human. So, I thought the 150 DC to tightrope walk on clouds was a bit absurd.
Al Qadim was a great setting, and I think there is a great interest in the Middle East now. If WotC wants a broader book, maybe come up with something that covers this part of the world and have Al Qadim as an example of how to implement these rules.
I also liked Oriental Adventures, but I preferred Kara Tur to Rokugan, as there were more varied cultures.