Kanako's is literally useless since she should never be in the 4th slot anyway so she can make use of her bulkiness.
Kanako -can- be decently durable, but if you don't encourage that in her build then she becomes frail enough that it doesn't really matter. Unless you really pushed her tankiness for some reason I don't see why you would ever put her in slot 2, and slot 3/4 aren't terribly different IMO now that LoT1-style row attacks are much rarer. (Suwako's is too weird to even bother with, poor Suwako, she doesn't seem much good this time around, unless Long-Arm-Long-Leg can do better than I thought with KeroKeroPower)
Also, Ghaleon, I'm still using Rinnosuke because high boosts are godly when maxed. It takes 30 points to max one, but it sends that stat higher than anyone else in your party probably has, so once you've got some levels he can be a stellar tank (and it just keeps getting better the more you have)
Just picked up Yuuka, she's vastly easier after the 1.20x patches. I remember before my party just got utterly destroyed by her even though they had basically the exact same library levels and equipment on. (She still wasn't easy, though, for sure) That or I'm stupid and never got my buffs up last time I guess. Man, Nitori's maintennance is too good, pump those resistances girl.