Emily is pretty but I prefer all of the other three. Matilda is my favourite by far. All nice names though and all go well with George and Peter. I don't think you can lose with any of them.
But if you want other ideas, then I also think George and Peter go well with:
Amy, Abigail, Alexandra, Bethany, Bryony, Claire, Chloe, Danielle, Daisy, Emma, Eleanor, Erin, Frances, Florence, Grace, Hannah, Harriet, Holly, Isabel, Imogen, Jessica, Joanna, Jennifer, Juliet, Katie, Katherine, Lily, Lydia, Lucy, Madeleine, Melissa, Miriam, Molly, Naomi, Natasha, Natalie, Olivia, Phoebe, Philippa, Rebecca, Rhiannon, Sophie, Sarah, Stephanie, Susannah, Tabitha, Victoria, Vanessa, Zoe