I think farne needs infinite time skill on saw, she's black goddammit why make a black garbage af... Only then she can match with some blacks. Seriously placing pallis is generally a safer choice than farne on my alt...
If you want individual names and (looks like) not care about looks but usefulness then i'd go with b. iris, leone, estelle, sophie, minerva, alice and nanaly. Other blacks are useful on their own but these alone will carry you through at most events/story quests with a little help they need. Cant say only one name, its you who will decide in the end.
I agree about cornelia and fredrica but you know dmm whales, they get what they want! i dont think it has to do with bad luck not being able to get them tbh also here i'll make you life easier
轟雷のフールフール
魔神アガレス降臨
魔神ウェパル降臨
剛炎のアモン
魔神ビフロンス降臨
these are jap names of all majins, just put 15 in front of them and search it on at http://www.nicovideo.jp/ only look at the teams there without advancing more. Seriously the only majin that estelle got used is the fish one (vepar) Havent seen her much in others especially at agares. Agree with nataku and sophie tho, they are effective with individual enemies and deine is viable too as long as she's not holding 4 bosses at once. Im maybe not a dmm veteran but i do know how to search things and dont care about majins at all really, otherwise i'd picked only b. iris on all accounts i had.