Top five science fiction novels since 1945 (can't believe I haven't done this, but search didn't turn up anything):
1. Ubik (Philip K. Dick, 1969)
2. Blindsight (Peter Watts, 2006)
3. Neuromancer (William Gibson, 1984)
4. The Left Hand of Darkness (Ursula K. Le Guin, 1969)
5. Dawn (Octavia Butler, 1987)
This was really difficult for me, and honorable mentions include:
Rendezvous with Rama, by Arthur C. Clarke (this one didn't make it because Blindsight is basically RwR updated for a neuropunk future)
Do Androids Dream of Electric Sheep? (decided to go with Ubik; but honestly, I could have put a few PKD novels in my top five)
The Female Man, by Joanna Russ (so many great '70s feminist sf works, I went with Left Hand)
Stars in My Pocket Like Grains of Sand, by Samuel Delany (awesome political sf, might be in the top five someday)
The Dispossessed, by U.K. Le Guin (again, great political sf; but I already have Le Guin on there...)
So many more...