In almost every respect, a 1x18650 light is better than a multi AA light. But, it’s not better from a safety perspective, nor are 18650’s as easily available (and you have to be sure to get genuine cells).
A bright 2xAA light I can recommend to anyone, even the dumbest of my friends (and I have some really dumb friends). I’d only recommend 18650’s to someone who is careful about battery tech (which is zero of my friends). Though, I suppose a protected cell might help with some of my smarter friends.