I like Emmie, Ada and Maisie from your lists (but would also use Emmie as a nickname for an Em name).
Otherwise, I think Hallie goes well with:
Amber, Amy, Alexis, Aubrey, Avery, Bella, Bronte, Bonnie, Cassidy, Cleo, Cecily, Darcey, Dina, Delphi, Etta, Eden, Effie, Fallon, Faith, Fleur, Grace, Giselle, Georgia, Harper, Hazel, Harmony, Ivy, India, Iris, Josie, Jasmine, Joelle, Kayla, Kendall, Keziah, Kayleigh, Kiki, Lola, Lila, Leona, Livia, Lena, Layla, Mimi, Macie, Marnie, Madison, Noelle, Nova, Nyla, Nia, Orla, Piper, Pippa, Paige, Phoebe, Quinn, Ruby, Romy, Remi, Rhianna, Rosina, Saffron, Skylar, Sylvie, Saskia, Sabrina, Taryn, Tegan, Thalia, Una, Verity, Veda, Vera, Willow, Willa, Winnie, Zia, Zeryn, Zoe