Well, as said before, Asimov's great achievements were not on the tech side of SF (altough he managed some marvellous predictions: e.g. scanner pen cf. Cpen) but rather on the psychological and social.
(robotics & psychohistory both currently under serious consideration of people in the respective fields of research)
Same goes for Heinleins "Stranger": Altough his prediction of a water bed was precise enough to lead to a later denial of a patent due to prior art, his achievement in said book was working on the question in how far acquisition of psionic skills (or if you want the fantasy glasses: magic) would change society.
When judging an author's attempt to make tech predictions, never lose the tech level they live within out of focus. Verne was a well chosen example.
For a hardcore comparison read:
"Warp Speed" & "The Quantum Connection"
Unless you keep in mind that Doc is @ home in these sciences you'll think it's the biggest heap of makeuppium ever seen - until you read his notes on the scientific background of it all.
Re Dune: De gustibus...
IMO the last three volumes of Dune are far away of being labelled greatest for whatever reason. Tastes differ.