4* Awakening Gem Conundrum

BluDragon

I am about to finish exploring Act 4, and am trying to decide who I should use the awakening gem on. I think there are four clear choices. To set the scene a little, I already have awakened 4* Wolvie, Iceman, Angela, Voodoo, Blade and Luke. I do not have a Scarlet Witch, who would be my first choice if I did. Should I wait for her or use it on one of the following?