Okay, I am Level 40 and want ADCs. I will get Lucian no matter what but I have enough BE to get both. Is it worth getting both? What are the cases where I would pick one over the other? For example, when would Kai'sa be a better pick than Lucian?
Thanks for the help, LelsersLasers
Lucian is more of an AD caster, he deals damage with his abilities and passive
Kai'Sa is a hypercarry, deals damage with basic attacks
In Iron-Gold it won't matter what you play if you can play it well enough, and you will climb.
I'd say if you have a good frontline, Kai'Sa is better and can deal more dps in extended fights (Late game-Team fight comp)
In more skirmish comps Lucian is better because he's slightly tankier and you build hp 
and lifesteal 
on him (Mid game-Skirmish comp)
Kai'Sa is balanced for Pro Play, so I really wouldn't go near her as a new player
