Stranger in a Strange Land was a bit too predictable for my taste although it was an entertaining read to some degree - but I found Dune much more interesting and worthy of praise.
First time I tried to read Catcher in the Rye I found it dull and didn't get far, but the second time I got into it and really enjoyed it. I ended up feeling a lot of sympathy for the main character.
Dune is more profound, but as far as predictability goes, it's almost a one-way street as a book. Which is not to detract that it is very good, and that Stranger in a Strange Land is similar, once the "church" is formed. I found SiaSL as giving interesting insights into what a completely weird alien species might be (much like Asimov's The God Themselves, a personal favourite.) I think that since these two are good, classic books picking one over the other is just a matter of preference, although Dune will be in far more antologies and SiaSL will be more an underdog. Do you have any SciFi recommendation, by the way?
First time I tried to read Catcher in the Rye I found it dull and didn't get far, but the second time I got into it and really enjoyed it. I ended up feeling a lot of sympathy for the main character.