H.B. I like most out of those three. My favorite quest line was Murderess but Celica and Nagi give good arts and have good stories. Alexa's line is the only way to get a level 60 skell before post game. Yelv has a good story and some great arts (essence exchange is the whole reason I use a light saber) but the end reward is a joke weapon. But yea, that's my thoughts on those lines.