You're not going to find a consensus, here or anywhere. It really does depend on your casebook, professors, and your own study needs. You can look through all the previous threads, but you might not find the answer that works for you.
So my vote for what are generally useful and wasteful:
generally useful: Emanuel's or Gilbert's, Examples and Explanations, using LexisNexis and Westlaw
generally wasteful: Legalines and CaseNotes, Nutshell, Crunchtime, flashcards (a lot of students disagree with me on that), multi-colored highlighters, those four-page condensed outlines.
in between: if you get Black's Law Dictionary, you probably will use it often. But it will gather dust after your first year.
nb: Hornbooks and treatises are good to study with, but don't buy them. Use them at the library.
nb: get a hold of outlines from students who have previously taken the class.