ISSA geared toward bodybuilders....
I went the ISSA course... Yep it's more expensive, BUT it was a personal thing... Personally the ACE course seemed easy and honestly seemed the easy route! All of the ACE certified folks that I knew personally I didn't respect AT ALL!! I'd NEVER listen to their advice or allow them to train me. But then again they were mostly "fitness" folks with 11" biceps trying to train people.
I feel that the ISSA is geared more toward the bodybuilder then ACE with the support of Dr. Squat Hatfield, and Tom Platz. ACE seemed more mainstream fitness let's get lean and not put on much size.
The two day Seminar was amazing! In ISSA you can attempt to pass the test without attending the seminar, but I doubt too many pass without attending. Tom Platz headed our Seminar and it was amazing to see him and listen to him for 2 full days! Not sure you'll get the same attention from ACE.
I really could care less if ACE is more recognized I wanted to join the certification where I would LEARN the most and could help the most people!!
Everyone has an opinion though...