Should I use ReservesDirect, Blackboard, or LearnLink?

That depends: LearnLink is best at creating student community, Blackboard is best at administering courses, and ReservesDirect is best at providing course materials. You can’t reserve a book in the library with Blackboard, and you can’t upload a journal article or book chapter into Learnlink. You might want to use all three; you can export ReservesDirect courses to both Blackboard and LearnLink / FirstClass. See this chart for a full breakdown of the features of all three programs.