experience in those classes, since most of the kids who don't care about school won't be there, and the odds of having a good teacher in an AP class are higher (not a guarantee, but the odds are better).
Reasons to not take AP classes: normally they are quite a bit harder than the regular classes, so there's a chance of getting a worse grade. Some say that a B in an AP class is equivalent to an A in a regular class, but BYU doesn't agree. If taking AP classes tanks your son's GPA, it will hurt his chances getting into BYU.
And if he doesn't get a 3 or higher on the test, he won't get any college credit, so that part isn't a guarantee either. For that reason, some people argue that it's better to take concurrent enrollment (actual college classes) if available.
Our kids took AP classes (one took as many as he could), and it worked out well for them. I think it works out well for many kids. But I know some cases where it ended up being a mistake.
So it's not a slam dunk decision.