ACE is ok....little on the easy side. There's a bunch of them out there but I feel that the key to personal training is that the person is educated, insured, and motivated to provide quality service to their customers
The only reason why I keep my NASM-PES and NSCA paid is for the sole purpose the coaches I work with want it. Other than that they are pretty much useless in the general population. However, our specialty certs carry a lot of weight in our private business. FMS, NKT, USAW have more use than a PT cert even a CSCS.