If you pick a base character then the prime gets removed as well, the better version cant exist without the base version, however if you remove a prime version then the base character can still exist. My personal pick would be Valkyr due to how [IMO] useless she seems
Yareli, purely on an artistic perspective. This anime stuff can go to hell for all I care x)
but she has the best fabric physics in the game, almost everything else is so rubbery :(