Dune, by Frank Herbert
The Forge Of God, by Greg Bear
Dune is a great one to have on the list.
I've only read the first, I should probably read the others, but I just keep rereading the original
I would honestly recommend not reading the rest of the series. They are very different than the first book and tend to be much more philosophical/political commentary. I would say maybe read the whole thing once, but Dune is the only one I have read multiple times.