Gastly line of course. How is this even a question? Haunter and Gengar are still some of the coolest pokemon ever. Chandelure is powerful, but come on, its a chandelier --- Rainbow Dash is best pony. The only arguement I will accept is for Twilight Sparkle.
bluhhh, both lines are like, my favourite Ghost-types ): who to piiick
I'm gonna go with the Litwick line, mostly because they're adorable and have a better design imo. Gastly line is basically just STEREOTYPICAL GHOSTS, but they're still p. pro! but yeah, the cute haunted lights for meee :3c --- -the benevolent artist
Everytime I think of "ghost type" gastly line comes to mind. I love the mischevious bastard, they're pretty original and are unique for their typing and design. Great pokemon overall since the beginning.
Litwick line is refreshing. Fantastic typing and a fun design. But rather generic. Candle-Lamp-Chandelier. But it's pokemon so you can't be too picky. Chandelure still looks dope though.
I'd have to go with Gastly line for the better design and general badassness.