Here are my three picks:

1.Imaginative Realism
From what i gained through james gurney's blog about illustrations, I believe it is the best book for aspiring fantasy concept artist.

2.Exodyssey
Always loved their work. They have very cool shaped designs. I believe it one of the best for concept and industrial designer.

3.Art of Up
Beautiful and cute characters and charming colors, how they were made, thats why.