Surely you're just going to get lists of the friendly people that individual posters have known.
But, fwiw, I suppose I think of nick-namey type names as being friendly as they suggest a certain level of informality and closeness:
Girls:
Abbie, Amy, Annie, Ali, Becky, Bryony, Billie, Charlie, Connie, Cassie, Callie, Carly, Casey, Chloe, Daisy, Darcey, Danni, Ellie, Evie, Effie, Elsie, Esme, Edie, Frankie, Gracie, Gabbi, Halle, Hayley, Heidi, Holly, Hannah, Izzy, Jessie, Juliet, Jodie, Katie, Lily, Lucy, Leah, Lydia, Lisa, Maisie, Maddie, Nikki, Natalie, Phoebe, Poppy, Rosie, Sarah, Sophie, Sadie, Tilly, Vivienne, Zoe.
Boys:
Alfie, Archie, Adam, Bobby, Charlie, Dominic, Dylan, Felix, Harry, Harvey, Harley, Jonty, Jamie, Jack, Jake, Nicky, Robbie, Sammy, Timmy, Tom, Vinnie, William, Zach