This one's tough. I feel like while they care for each other Linda and her aren't that close. Eve and her even less so. Dan and her were always close but I wouldn't label them as "best friends". I'd say right now Ella and Maze are her bfs, but I'm not sure they top Lucifer. And, even if they did, I feel like which one she's closer to varies from few eps to few eps. So, I'm gonna go with Luci.