Yeah, again, never used Maul so not sure about him. You could always just save them a little longer and if you start getting a solid Empire team that you want to raid with, hit up Vader. Kylo is really strong and has helped me beat some darkside missions I probably shouldn't have, Omega challenges that normally I wouldn't have finished, and the Offense Mod Challenge T3 that I would have had to invest a ton more into other FO character if I was ever going to hope to 3*
I did Vader 1st, though and don't regret it, as I usually top the boards in our Rancor Raids.