Should I buy a dated or undated weekly planner?

Dated planners (like academic-year or January-start books) are best if you want structure and won't mind unused pages if you start mid-year. Undated planners let you begin any week and skip weeks without wasting paper, which is why several of the highest-volume sellers in this pool are undated. Choose undated if your schedule is irregular; choose dated if you want monthly calendar spreads and reference dates built in.