According to the IMDb, actresses considered for the part of Scarlett O'Hara were Jean Arthur, Lucille Ball, Tallulah Bankhead, Bette Davis, Claudette Colbert, Joan Crawford, Paulette Goddard, Katharine Hepburn, Olivia de Havilland, Carole Lombard, Norma Shearer, Barbara Stanwyck, and Margaret Sullavan. Candidates Louise Platt, Tallulah Bankhead, Linda Watkins, Adele Longmire, Haila Stoddard, Susan Hayward, Dorothy Mathews, Brenda Marshall, Paulette Goddard, Anita Louise, Margaret Tallichet, Frances Dee, Nancy Coleman, Marcella Martin, Lana Turner, Diana Barrymore, Jean Arthur, Joan Bennett and Vivien Leigh were given actual screen tests for the role of Scarlett.
Personally, I like Lupe Vélez for the role of Scarlett O'Hara. It would have cut out at least an hour of self-centered whining, fiddle-dee-dee stuff, and that home-to-Tara nonsense. Lupe would have done Rhett Butler in the library during the very first party. And Lupe, not Clark Gable, would be saying the "Frankly, my dear..." line, and Gone With The Wind would have a running time of maybe 90 minutes. Which would have been a lot more interesting.
Of course, Frances Dee is my favorite.