I really like both of them. Lampent is sort of meh, but Litwick and Chandelure make up for it. I've never actually used a Gengar (mainly because it's a trade evo, and I haven't had too many opportunities to get those), but I've always sort of wanted to. I did use Chandelure and it worked quite well for me.
I'm going with Gastly, because ... I was indecisive and asked for someone else's opinion, and he voted for that one. --- If you actively hate Justin Bieber... then you don't know what "intended audience" means. Hate Twilight instead, it's far worse.
Gengar's overrated, I think. Haunter's design was so much better.
Anyway, I'll give the point to the Chandelure line overall. --- "Hey look at me! I'm the rape stork. I drop off all my babies directly at the orphanage." -Bill Nye the Science Guy on Congressman Todd Akin
Hmm, Litwick line has the numbers and Gengar looks like a little fat man, but Haunter is just awesome. ...despite Haunter's awesomeness I'm gonna go with the Litwick line, since Litwick itself is pretty cool while Gastly is just a blob. --- The man in black fled across the desert, and the gunslinger followed.