Just finished reading "Fiasco" by Stanislaw Lem. Between that "Cyberiad" I feel like Lem doesn't get enough credit. Maybe part of it is not being in the Western European writer's camp?
At any rate, I would say:
Moon is a Harsh Mistress, Heinlein
The Dispossessed, Le Guin
The Stars My Destination, Bester
Childhood's End, Clarke
Stand out as some of my favorites. I'm pretty terrible at making top-5 lists, but those stand out as ones that I would read again in a heartbeat if there weren't already 50 books on the floor next to my bed waiting for me :)
If people knew of him at all, I'm afraid the Solaris films really damaged people's perceptions of Lem's work.
I've been reading his stuff since 1986 and he can be as innovative and experimental as Philip K Dick, JG Ballard, or Thomas Pynchon while still being fun and readable.
At any rate, I would say:
Moon is a Harsh Mistress, Heinlein
The Dispossessed, Le Guin
The Stars My Destination, Bester
Childhood's End, Clarke
Stand out as some of my favorites. I'm pretty terrible at making top-5 lists, but those stand out as ones that I would read again in a heartbeat if there weren't already 50 books on the floor next to my bed waiting for me :)