I first read Dune (a Catalan translation) when I was 12, and more

than 30 years later I still go back to the original series every couple

of years. Again and again and again... and I keep finding things within

things within things every single time.

Dune is

on a league of its own. There are many other fantasy (I don't consider

it sci-fi) series that are master works, but the world-building and the

writing really set it apart.

If you want to try

more "conventional" fantasy, the rage these last couple of decades is

the "grimdark" subgenre, and within that, all you really need to do is

read Joe Abercrombie's First Law Trilogy.

For

more conventional modern sci-fi, you can't go wrong with The Expanse by

James S A Corey, which is a pseudonymous for Ty Franck and Daniel

Abraham.

Who, by the way (Abraham) also has a fantasy series called The

Coin and the Dagger which was extremely enjoyable to me, and another one that I don't know any woman who hasn't fallen in love with for its incredible world building in a sort of pseudo-feudal Japan setting with magic and poetry: the Long Price Quartet (I enthusiastically recommend it regardless - woman, man or whatever).

In any case, really, have you read the "classics" such as The Lord of the Rings (Tolkien), or the new classic A Song of Ice and Fire aka Game of Thrones (George RR Martin)? And in sci-fi Rendezvous with Rama (Arthur C Clarke), the Foundation series (Asimov), any of Philip K Dick's (Blade Runner, etc)...