What are the best books for 8 yr old BOY?

It depends on what the kid likes; what does he like? Any cartoon books would be good though. If he is really into vampires, read the Cirque Du Freak series by Darren Shan they're awesome, or even read him a varieties of the back of books and read it to him.

At this age, for most kids it's still a good idea to read stories with one a parent, who can explain the more difficult Words/parts. This is also a factor in choosing appropriate books.