I think research would look better than pre-law club unless you had leadership in that club. Research also can get you more involved with a specific professor, who may eventually write a letter of recommendation for you.But the most important thing (and I think you already understand this, but I want to reiterate) is to do what you're actually passionate about doing. You may be passionate about a certain issue or cause, but not everyone's passions must be manifested in the same way (i.e. not everyone likes participating in clubs) and there's nothing wrong with that. Keep yourself happy first, worry about the resume later.