for design Takeda Mei easily. Oda Sayuri's design is badass too. it just screams Oda Nobunaga to me.
For Skills I absolutely love Lu Wu. unlocking her and building up her to be in my team is prolly the best thing I ever did. I'm also starting to become a big fan of Ren Qing cause her basic attack seems to proc the Skill Rate Up at about a 90% rate so it's very reliable!