That really depends on the topic you’re wanting to learn about. A few that were particularly impactful for me on a broad range of subjects:

Caliban and the Witch by Silvia Federici was a really great analysis of the division of reproductive labour and the persecution of women (and queer people/sexual deviance) as a form of controlling accumulation during the transition to capitalism.

Border & Rule by Harsha Walia was a very in-depth look at the ways that borders are leveraged to create sources of hyper-exploitable labour, and the ties between movements of reaction and racist nationalism. The precarity of vast swathes of humanity, and the violence imposed on them is made possible through the buttressing of mobile, militarized borders.

We Do This 'Til We Free Us by Mariame Kaba is a hopeful examination of restorative and transformative justice practices and the quest to craft an equitable society free from the violence of the carceral punishment system.

Transgender Marxism is a fantastic collection of essays by many different writers that shows the wide array of socialist currents in transgender organizing, and that helps to situate trans liberation within a wider socialist liberatory struggle.

Abolition. Feminism. Now. and Are Prisons Obsolete? by Angela Y. Davis are both fantastic looks at the necessity of prison abolition in feminist movements. There is no feminist victory within carcerality, and there is no freedom from carcerality within patriarchy.

Conquest: Sexual Violence and American Indian Genocide by Andrea Smith can help to situate the intersection of feminist action and Indigenous sovereignty, with a look at the ways that sexual violence were integral to the colonial project, and how the women’s movement shifting to “pro choice” as a defining single-issue of struggle left out the ways that “choice” can not exist for women in a racist colonial class system that deprives large portions of women from exercising any “choice” over their bodies at all.

Rainbow Solidarity in Defense of Cuba is a collection of articles by Leslie Feinberg about Cuba’s queer rights movements, and it’s super good for getting an inspiring framework for understanding how a worker’s state can offer true liberatory possibilities for queer people. Especially the articles detailing Cuba’s response to the AIDS crisis are incredibly moving.

Gender Trouble by Judith Butler is a bit of a deeper philosophical read, and unless you have somehwta of a grounding of psychoanalytics you might not get much from a lot it (you can read Shulamith Firestone’s The Dialectic of Sex as an intro to feminist takes on psychoanalysis, but I don’t agree with most any of her conclusions and am not really into psychoanalytics). However, Gender Trouble also had a massive influence on feminist philosophical currents, and builds really well on Simone de Beauviour and Michel Foucault in analysis the social construction of gender, and further, the way that sexual dimorphism and a biological sex binary is itself a social construct.

Trans Liberation: Beyond Pink and Blue by Leslie Feinberg is a collection of keynote addresses that can be quite emotional looks into the early development of gender deviant movements in the US.

Transgender Warriors by Leslie Feinberg is part autobiography, part trans history, part class analysis and part Marxist call to action. It explores hir own life as ze came of age as a masculine female during the McCarthy era, and then through hir labour in a factory grew consciousness regarding the exploitation of workers before finally joining a Marxist party, embracing communism, and spending hir life advocating for socialist revolution and trans liberation. It also charts early communal societies and the sacred role that trans people often played, and the arrival of anti-trans, and anti-homosexual sentiment as wealth accumulation began and class divisions first cemented. As well are snapshots of trans and gender deviant people throughout history.