Wedding Dress Lin

Wedding Dress Lin is the ultimate buffer. She buffs ASPD, MSPD, Crit Rate, Crit DMG, and MATK by their known highest (buff) amounts. Apart from that, another thing going for her is the "1 shield / 4 turns". I've personally had it come to effect at crucial moments: extra shields never hurt anybody. After Elle, shes definitely set to become the healer everyone brings to every fight.
An important note, however: She won't be replacing anyone permanently. Kino still has a 25%/40% PATK buff and bleed resist. Celenia still has 20% HP and 20% MATK reduction buffs. Lin has a different pattern of shields and decreases enemy Crit Rate and Crit DMG. However, WL (Wedding Lin) is now the best choice "in general" when you're just looking for more damage.