Miss Fortune wins lane because of raw overtuned stats.
Especially her ult, it lasts longer then it should and the moment she hits 6 shes pretty much guaranteed a kill or 3 with it.
I really think Riot needs to address numbers with her, specifically on her ult and Q, the power behind her ult honestly makes it the most damage in the game and the fact that it can wipe out an entire team really says that the numbers behind it are way higher then they should be.