Research dollars isn’t a great measure. Because the research is being done mostly by grad students at those colleges. An undergrad sometimes can get some research experience, but a lot of the time they aren’t working directly with a prof (working with grad students). And often research is tough to get as a frosh or even sophomore. Smaller schools that don’t have grad schools often can offer opportunities sooner and more responsibility because there are no grad students to help the profs.
Go to a research university for grad school. But it isn’t necessarily the best choice for undergrad.