Here is a link with a list you might find interesting. It makes it easy to compare based on time and background required to earn each one. Livestrong also does not offer one itself, and I think it is helpful to get input from informed people without a stake in the answer.
That said, though ACE does offer certification itself they have a good tool to let you do side by side comparison on a wide variety of points
AFAA personal training is not accredited by the NCCA, which while not the only point to consider, is an important point.
I have ACE for group fit. I used to carry ACE for personal training, back in the 90s, but closed my business when my family moved and I did the ‘mommy track’. If I decide to go back into that part of the business again I would probably do ACE, but that is because: I am familiar and comfortable with the organization, they are NCCA accredited, and I am already well connected, and have students who have expressed interest if I were to train.
So what i am saying is that there is no one best certification…. it depends on a lot of factors. The baseline, I think is to try to get one with NCCA accreditation. You might also look at some of the local health clubs and gyms and see which certs they accept (even if you are planning to teach independently it will give you good info on what the standards are locally).