I would go 1, 2,4,3,5. Its a little tricky because benzylchloride I think is a good SN2-electrophile as well but t-butylchloride is really bad and will give only SN1. But I think a benzyl cation is more stable than a 2-butylcation. Maybe its a trick-question and, as you suggest, 1 and 2 are very similar.