Sophie and Jessica - kind of solid, British, 80s-00s popular names aren't they.
I have a Jessica and a Savannah. Savannah is same letter as Sophie but a different type of name I think.
Similar to Sophie in my mind would be:
Amy, Abigail, Annabelle, Bethany, Bryony, Charlotte, Chloe, Claire, Danielle, Eleanor, Emily, Erin, Fiona, Georgia, Hannah, Harriet, Isabel, Imogen, Jennifer, Joanna, Katherine, Laura, Lauren, Louise, Leah, Madeleine, Melissa, Nicole, Natalie, Natasha, Olivia, Rebecca, Rachel, Rosie, Sarah, Samantha, Stephanie, Victoria, Zoe.