I prefer Eva. Her plan being to go after Joseph after trapping her from the real world for so long is kinda a dark mirror of Barry and Iris's relationship and frankly that dynamic was better than the other villains. Gemma was a pawn for Lex, the Fates were just repeating the Legion's plan from Season 2 of Legends, and Grace was a poor way of creating a dark mirror for Nora with no intrigue.