I recommend The Tripod Trilogy by John Christopher. As a kid I read The White Mountains blind and the story unfolded in a fantastic way for me. It is YA sci-fi and a lot of the themes are well-trodden at this point, but the story is strong and clear, kind of a coming-of-age-amongst-aliens.
There was a TV series back in the 80s which I really enjoyed - I actually checked out the books from the local library after having seen the show at the time.
I read the Tripod Trilogy to my little brother and we both loved the story. It's one of my favorites to this day. Going further back, I also liked Wells's "The First Men in the Moon".
