Some classics, in no particular order:

Charlotte Perkins Stetson, 1898. Women and economics: A study of the economic relation between men and women as a factor in social evolution.

Josephine E. Butler, 1896. Personal reminiscences of a great crusade.

Jennie Anderson Froiseth, editor, 1887. The Women of Mormonism, or, the story of polygamy, as told by the victims themselves.

Victoria Woodhull, 1870-1896. The Victoria Woodhull Reader.

Jane Addams, 1914 (reprint of 1912 book). A new conscience and an ancient evil.

Elizabeth Parsons Ware Packard, 1864, Marital Power Exemplified; 1868, The Prisoners' Hidden Life.

Sarah M. Grimké, 1837. Letters on the equality of the sexes, and the condition of woman. Addressed to Mary S. Parker, President of the Boston Female Anti-Slavery Society. IN Sarah Grimké and Angelina Grimké, 1835–1838. On slavery and abolitionism: Essays and letters.

Josie Washburn, 1909. The underworld sewer: a prostitute reflects on life in the trade, 1871-1909.

Margaret Sanger, 1931. My fight for birth control.

Also, Annie Besant wrote some stuff, including an autobiography. She was involved in publishing birth control information and was active against sex trafficking before she went New Age.

These are all books I've read. I'm not sure if any of them count as "best", but that may be a personal thing, too.

I have a book created in the 1970s by Blance Wiesen Cook I bought at a yard sale, Women and Revolution. It puts together the writings of Crystal Eastman who was active in the early years of the 20th century.

It's fascinating, because it has essays which address the kind of quarreling feminists have always been doing with each other and also the kind of support and sisterhood there has always also been when bad things happen. One essay talks about their views on women working night shifts, where some in the group wanted laws to stop women having to work nights because of the extra physical danger for them and others worried about the fact that women would then be less likely to be hired at all and wouldn't be able to earn as much.

But it has many other interesting essays, too. I have never seen it discussed so I have no idea how important Eastman was.

The one you just posted! :D Gilman's Dress of Women is another favorite. Alice Duer Miller's Are Women People? contains some hilarious poems.

On the other side of the pond, I found Lady Constance Lytton's Prisons and Prisoners particularly moving, and there's a fine anthology, Literature of the Women's Suffrage Campaign in England, edited by Carolyn Christensen Nelson.

The Awakening was my personal favorite.