I’m going to answer your question a bit differently than my predecessors.
Do you know where you want to work, or what kind of work you wish to do? What client populations you’re most interested in working with? If you have a real specific area of interest, take a look at the advanced trainings offered by ACE, NASM, and ACSM and see which of those also pique your interest. It’s often cheaper to stay with one agency if you are going to have multiple certifications. If you have a specific employer in mind, ask them what they prefer and why. I haven’t had trouble getting a job with ACE, but one of the places I worked was a NASM shop; I was the only person they’d ever hired who didn’t have NASM, but I had some specialty certifications they desired.
IMO, NASM and ACSM are slightly higher ranked than ACE. NASM and ACSM seem to be more close to the research, and ACE uses them as a resource material.