I think they're all reasonably popular but not ridiculously so.
I like Elodie and Darcey.
I do like Willow but I would worry about the child being teased if they turned out not to be willowy.
Less keen on Dorothy - it still seems quite old lady to me although I know it's very trendy now.
I think Elodie, Darcey and Willow belong in the same sort of style of names and would say others like them include:
Ava, Aimee, Alyssa, Amelie, Bella, Chloe, Cleo, Caitlyn, Daisy, Emily, Evie, Freya, Gracie, Georgia, Holly, Hallie, Isabella, Isla, Jessica, Jasmine, Katie, Lily, Lucy, Layla, Lola, Luna, Matilda, Mia, Molly, Millie, Olivia, Phoebe, Poppy, Ruby, Rosie, Sienna, Sylvie, Sophie, Sophia, Tilly, Zoe
I think Dorothy is a bit different and think it is in the same style as names like:
Annie, Agnes, Agatha, Bonnie, Betty, Betsy, Carrie, Daphne, Elsie, Esme, Edie, Edith, Flora, Florence, Greta, Hazel, Harriet, Ivy, Iris, Joyce, Jocelyn, Lydia, Louisa, Maggie, Martha, Mary, Maisie, Nancy, Nora, Nell, Olive, Peggy, Polly, Queenie, Ruth, Rose, Rosemary, Susan, Stella, Tabitha, Teresa, Violet, Winifred