Is it better to take higher-level, more specialized courses that show interest and ability in a subject area… or is it better to take courses that are only first- and second-year level and easier to receive transfer credit for across different universities?
Both, ideally. You typically need to take all of the same first and second year courses, because those courses are generally fairly standardized across most schools. However, if more advanced courses are available, they should definitely be taken. Even if you don’t necessarily receive credit for a requirement for a given course, you’ll still benefit by the greater exposure. The fact that you’re taking on more than the minimum counts for a lot.