Nearly every name has different spellings or a few variants, especially if it's commonly used in several countries. Here's a list of my preferences — it's either because I think a particular version looks nicer written down, or I like the pronounciation of it more.

➤ feminine

• Abbie, Abigail, Abigél
• Adel, Adél
• Adelaide, Adelheid
• Adrienne
• Aggie, Agnes, Ágnes, Nessie
• Alice, Alicia, Alícia, Alíz
• Amália, Amelia, Amelie
• Anastasia
• Ania
• Anna, Anne, Annie
• Annabelle
• Aurora, Auróra
• Beata, Beáta
• Belle
• Caitlin
• Camille, Kamilla
• Christine
• Danielle
• Dominika, Dominique
• Eleanor, Eleonóra
• Elise, Elsa, Eliza, Elizabeth, Liza, Lizzie
• Elle, Ellie
• Emilia, Emília
• Eva, Éva
• Evelin, Evelina, Evie
• Gabriela, Gabrielle
• Greta, Gréta
• Hanna
• Helena, Heléna, Helene
• Isabelle, Isobel, Izzie
• Jacqueline, Jackie
• Josephine, Jozefa, Posie
• Julia, Júlia, Juliet
• Julianna
• Karolina
• Kat, Kate, Katherine
• Letícia, Letitia
• Lotti, Lottie
• Louisa, Louise
• Maddie, Madelaine, Madeline
• Magdalena, Magdaléna, Maggie
• Margaret, Margareta, Margaréta, Margarita, Margot
• Maria
• Michaela, Michelle, Mihaéla
• Mónika, Monique
• Nadia, Nadine
• Natalia, Natália
• Nelli, Nellie
• Olivia, Olívia
• Ráhel
• Rosa, Rose, Rosie, Róza
• Rosalie, Rozália
• Rosamund
• Roxanne, Roxana, Roxána, Roxi, Roxie
• Sara, Sára
• Selena
• Susan, Suzie, Zuzana
• Sybil
• Viktória

➤ masculine

• Adorján, Adrián, Adrien
• Alex, Alexander, Alexandre
• Charlie
• Dan, Dani, Daniel, Dániel
• Dominik
• Elias, Éliás, Elijah
• Fábián, Fabien
• Jacques, James, Jamie
• Julian
• Kilián, Killian
• Louis
• Mark
• Nathaniel
• Nikolaj
• Robbie, Robert, Róbert, Robi
• Viktor