I would not make that assumption. Weaker departments at small colleges are often due to limited course offerings, so that taking all of the courses there would still be seen as “incomplete” compared to a larger department at another school. Checking course catalogs for offerings, and schedules to see how often each course is offered, can be useful. Also, sometimes a small department focuses on a particular specialty area within the subject, which may be great for a student into that specialty, but not so good for one who wants to learn the subject with the typical breadth of undergraduate learning.
For computer science, Davidson appears to be the most limited from your list. Amherst is fairly limited as well, but the cross-registration with nearby University of Massachusetts can fill in the gaps. But check the frequency of offering of courses at the others. If most advanced courses are offered only once every two years, that can reduce scheduling flexibility. Holy Cross has this problem.