I'm not overly keen on Karen. I don't think it's that dated though, I'm sure it must get used sometimes, if only due to Outnumbered. I prefer Karin.
Other K sound names:
Katherine, Kaitlyn, Katie, Kitty, Katya, Katerina, Karina, Karenza, Katinka, Kennedy, Kenzie, Kendra, Kayleigh, Kylie, Kelly, Kerry, Kelsey, Keeley, Kayla, Kyla, Kyra, Kia, Kaya, Kimberly, Kendall, Kinsley, Keira, Carol, Caroline, Carolina, Catriona, Catalina, Cara, Clara, Carla, Cara, Cora, Coral, Cornelia, Constance, Connie, Cassandra, Cassidy, Cassia, Cassie, Clarissa, Callie, Carrie, Courtney, Claudia, Crystal, Coco, Chloe, Carmen, Camryn, Camilla, Camille, Colette, Colleen, Cleo, Clea.