I think that, for you, a large good public university may be the best choice. Looking at you choices of privates, I would drop UPenn and UChicag, and replace them with Northwestern and Cornell. You could also add Rice, and drop NYU.
Of Liberal Arts colleges, most which have strong STEM have good Chemistry programs. So you can expand beyond Williams to other ones. However, you would need to figure out what other things are important for you at a college. Liberal arts colleges are small, and if you do not really fit, it can be difficult, so fit is more important than at a large research university.
Liberal Arts Colleges have advantages and disadvantages regarding research. On one hand, their mission is undergraduate teaching and research is secondary. On the other hand, all of the good ones emphasize undergraduate research. That means that if you work on a research project with a professor, you will be engaged in actual research, not in helping a graduate student. Research universities have larger labs and often more advanced research, but undergraduates generally are shunted to lower-level work, and they need to share attention with graduate students.
Of course, there is a lot of great research at liberal arts colleges, and an undergraduate who takes initiative can often have their own research project in research university.
As an aside, if you are looking at doing a PhD, by and large, a higher percent of liberal college students end up doing a PhD than those from research universities. However, the college which has the highest percent of undergrads who go on to do a PhD is Caltech.
Good luck!