Nsca, nasm and acsm are the most prestigious certs.

I'm a registered clinical exercise physiologist and also a fitness director for 2 health clubs, and prefer acsm over any other when hiring personal trainers. I also rarely hire a trainer that doesn't have a bachelors degree in exercise physiology or kinesiology.

Acsm has a bit more clinical focus, nsca is more athletics focus. Pretty much every strength and conditioning coach has a cscs cert from nsca.