Akali or Cass top?

Which do you think would perform better. I need to add an AP toplaner to my champion pool. I know most people would prefer Cass but looking at the success rate of higher skilled akali's is what's stopping me from committing to Cass. Both have their pros and cons. So lemme break this down into two questions: Which champion would you prefer to play in toplane and why? Which champion would you rather have on your team if you were playing another position and why?