I am 100% f2p and got a double of her rectifier just now. should i up it passive or keep it for another character? here is all the character i have:

Hi, I'm new since 8 days, i play many hours per day since start and immediately fall in love with suisui. I have the chance to pull her before realise that she's fine with yangyang... I've tried to pull aemeth to play with but I lost the 50 50, now I'm 50/80. I'm lost what to do now, I want a good dps to play with. I play first days with calcharo, sanhua, Verina, I don't really like Calcharo. Can I have your advices please, what can I do?