1. Answer: It depends on everyone's taste and these rankings change all the time. According to RankMyPorn, at the moment, the top ranked Ebony Female Pornstars in the world are: Nia Nacci, Diamond Jackson, Anya Ivy, Victoria Cakes, Scarlit Scandal, Mona Azar, Ms London, Cecilia Lion, Brittney White, Adriana Maya, but these will change based on what people vote.
2. Answer: It changes. You can see the latest rankings on RankMyPorn.com and also vote on it for free.