I have three favorite Heinlein novels. None of them are "Starship Troopers." "Troopers" isn't a bad novel, but I don't think it represents Heinlein very well. Most of his books weren't military science fiction. My three favorites are "Stranger in a Strange Land," "Double Star," and "Citizen of the Galaxy."
"Double-Star" is about an actor hired by an anti-racist group to impersonate a racist politician and use his influence to make things better for Martians in a human-dominated Empire. "Citizen of the Galaxy" is one of Heinlein's juvenile novels, and it is a touching story about the emancipation of a slave. These books condemn slavery and racism.
"Stranger in a Strange Land" is one of his longest novels, and also one of the deepest, and weirdest. It is about a young human orphaned on Mars by a lost expedition, and raised by an alien culture, who is reintroduced to human society as an adult and quickly becomes a controversial figure with the potential to radically transform life on Earth and humanity's understanding of ourselves and each other.
I devoured "Stranger in a Strange Land" in the summer of 1997, and I wanted to live in its world and be its characters.
As a more critical adult, I can understand why a lot of people don't like Heinlein's views (although they changed a great deal over time). His characters tend to become "ideal men" (they are almost all men) through heroic struggle, and that kind of narrative does attract a certain type, but not exclusively. His views were probably closer to libertarian in his prime than anything else, which is problematic, and there are plenty good criticisms of Heinlein (and a lot of good, about him too). Heinlein was many things- proto-libertarian, proto-hippie, dirty old man- but please do not call him a fascist, especially if the only book you ever read by him was "Starship Troopers." Or worse, if you only saw the Paul Verhoeven movie.
For the record, I like the movie. It's funny and has good social satire, similar to Verhoeven's other classic, "Robocop." But it's not a very faithful adaptation, and a lot of viewers missed the satire. Some people think "Starship Troopers," the book, was more satirical than Verhoeven realized... which makes this an odd recursive example of Poe's Law, if true.
Paul Verhoeven, famously, hated the book and didn't finish it. He seems to have gotten the wrong message. He confused this for Heinlein's ideal society. But it was simply one of many fictional societies Heinlein wrote about. The fascistic Terran Federation in "Starship Troopers" probably does reflect his most militant views, but it is not Heinlein's vision of an ideal society.
I know this because Heinlein did write about his ideal vision of society... in "Stranger in a Strange Land." It was a pantheistic New Age hippie commune called the Church of All Worlds, and it inspired much of the 60s counterculture, free love and all. Some have even referred to that book as the "Bible" of the counterculture. How quickly we forget!
There is also a real Church of All Worlds, an experiential, non-belief based neopagan organization based on the Church of All Worlds from the novel, which incorporates much of the Martian terminology such as "grokking" and "waterkin," important concepts in the Martian culture of the novel that the protagonist, Michael Valentine Smith, imported to Earth. For a time, "grokk" was a relatively common word, seen on tee-shirts ("I Grokk Spock") and heard whenever hippies got together. It really was a very influential book, to inspire an actual religion.
It's not my ideal vision of society. But it's definitely not fascist. Labelling Robert Heinlein a "fascist" because he wrote "Starship Troopers" (or because Paul Verhoeven didn't like or finish the book before he made the movie) is an ignorant use of that word. It diminishes the work of anti-fascist organizers and it diminishes fascism's victims.
It's also like insisting that Frank Herbert supported feudalism because "Dune" was set in a feudal culture. But I never hear anyone make that claim. They only seem to make it about Heinlein, and usually "they" have only read that one book (if they're not basing their opinion off the movie).
I'll go on record that Herbert, like Heinlein, also had some problematic views and was quasi-libertarian, at least later in his life. Heinlein's views evolved over time, and earlier Heinlein was practically left-liberal, but Heinlein is no more a fascist than Herbert supported the political system of the Empire of Shaddam IV. Remember that these are writers and the genre is called "speculative fiction." Neither of these books were political manifestos. "Starship Troopers" is military science fiction and "Dune" is basically speculative journalism (it was inspired by the Oil Crisis). But "Stranger in a Strange Land" arguably was Heinlein's political manifesto. And you should read it. It's a classic. And you'll understand why it's a shame that my generation only remembers him for "Troopers."