Those are both great programs, but of course CarND is better :-P
As you mentioned, CarND is narrowly focused on the self-driving car technology stack and helping students get hired for jobs working on autonomous vehicles.
AIND covers AI more broadly and teaches a wider variety of tools that can be used in many different domains.
If you want to work on autonomous vehicles or robotics or something similar, you should take CarND. If you want to use AI in other, much different fields, AIND might be a better fit.