Having visted Dartmouth and CMC, and knowing students who are attending or have attended both schools, I would say that they are both incredible. But there are differences between the two - their student bodies, their culture, their curriculum, their locations, and even things like traditions, clubs, and food, but the things that someone else notices or cares about may be very different than the things that matter to you.
Your indecision is normal. It’s also telling. I know many, many students who have changed their minds on which schools they favored between the fall application season and when decisions came out in the spring. Many. You might be one of them. Why commit now when you’re not sure?
My best recommendation would be to apply to both RD. If you are fortunate to get accepted to both, you can visit the admitted students events and decide which one feels like the best fit for you.