Both are great schools. I don’t think there’s a significant difference in terms of prestige. On one hand, you have the best college consortium in the US. On the other you’ve got what is probably the top academic D3 conference in the country. Knowing nothing much at all about you, I’d probably recommend Pitzer. It’s near a big urban environment, and it shares resources with four other first-rate colleges.
My son is at Williams, so I’m a big fan of the NESCAC schools including Bates. But for your average international student, I’d probably recommend Pitzer and the CMC.