I looked extensively at this myself a while back - I was in the exact same spot you are right now. I emailed Cy Wilson who recommended these:
I found these are considered standard for the industry as well:
Then there's one that all of us like to bash and poke fun at:
ACE - I love to rip on anyone with an ACE certification. It follows the same lines of wearing a hat that says 'im #1'. It just doesnt sound credible.
However, ACE is, unfortunately, very highly respected, and if im not mistaken, is the standard used by well-known universities for those majoring in exercise science or phys. ed. Most gyms would consider an ACE certified PT ahead of others who hold different certifications.
These are the certifications to avoid at all costs (with the exception being if you're flat broke, wont be able to eat for a month, live in a carton box and have a sign that says 'will suck dick for food' - then you're justified in choosing these):
IFA - simply put, they're a joke. $99 express certifications. download a pdf book, download your exam, and then submit it. Redo it until you get it right. Then make your payment, and your ta-da, your certification will arrive in the mail within a few days.
NESTA - they've been gaining ground, and if you do need a cheap certification, I would choose them. However, their reputation isnt, well...they dont even have a goddamn reputatino. People will think youre just making it up and that you went to your local office max and made your own card.
Every other organization not listed here is not credible. Steer clear of any organization not recommended here.
If I had to put these in order, starting with the ones most likely togive you a good name and a hired faster, I would do this:
Good luck!! Hope this helps! Just remember to read Charles Poliquin's books, frequent t-mag regularly, charlespoliquin.com, johnberardi.com, and you should be fine.