AP Stats isn’t a slacker class. And in fact, it’s a very useful class with practical applications. If you are interested, take it.
You seem to have plenty of rigor so far. My thought is that you shouldn’t take things just because you think they will look good to colleges with minuscule acceptance rates. It seems that you will enjoy AP Art History more than AP Env. Sci. You should enjoy your last year of high school, not just try to fulfill a preconceived idea that really selective schools expect to see all kids take the same classes.
P.S. Stats is math.