you do not need to have CPR and AED as a prerequisite to enrolling in any fitness certification course but you will not receive the certification document until you show proof of having completed it.
As to the second part of your question: there are many to choose from, and in part it is a matter of accessibility and preference. I strongly suggest that you look into certifications that are NCCA accredited. You can start on this website http://www.ideafit.com/fitness-certifications where you probably have the most comprehensive overview of them all.
ACE has a comparison between certifications which may give you more insights https://www.acefitness.org/fitness-certifications/personal-trainer-certi….