Weird comparison but I am mainly asking because for berserkers, I really only have Lu Bu who I just recently got and raising him quite a bit and as for assassins, I joined right after the Ryougi Shiki event so I really don't have any assassins to help fill the role aside from 3 star ones who I have been ignoring sadly. I might even consider Tamamo Cat for farming purposes. Really on a welfare budget and saving all of my quartzs for what is to come like Ozymandius or Minamoto no Yorimitsu.
Go for Herc. He's one of the best SR in the game rn, and will be even better with his Bond CE. He definitely has the "carry potential" for you in multiple events and challenge quests so you'll get a lot more value out of him than you will from Carmilla (who is a good servant in her own rights).
Herc is your safest bet if you do not get Raikou. Even if you get her, Herc will outshine Carmilla due to his damage and survivability. If you lack Assassins, the closest 4 star you can get is Scathach in summer event.
Getting Herc is your best answer. I'm planning to get him since I don't have a 4- 5 star Berserker. At least I will be less saltly if I don't get Irabaki Douji.
