Ursula K. Le Guin, The Dispossessed: An Ambiguous Utopia (1974). Le Guin's fairly brilliant imagining of a well-established "Odonian" revolutionary anarcho-syndicalist society on the moon Annares. It sets out a utopian vision via a stress test of that vision. The novel is absolutely an anarchist-syndicalist polemic -- to think otherwise is a serious misreading! -- but it dwells on the fragilities and flaws of the society it advocates.
Books like these are really carrying the whole SFF team. Really: The Disposssessed is getting toward half a century old, and is still in many ways the first go-to book for speculative fiction and political economy. That's a testament to the great insight and imagination of the novel itself, of course. But it could also be a wee bit of an indictment of what we've all been up to since then.
A huge amount has been written about it, but I haven't come across any attempt at a brief summary of the key economic institutions and practices of Annares. So I've attempted that below. If you think I've bungled something, please let me know!