Both work. The instinct on a honeymoon is "we want it to ourselves" — on that test,
Mozambique wins. The Bazaruto Archipelago has five islands shared between a handful of small luxury lodges; you can spend an afternoon on a sandbar and not see another boat. Zanzibar honeymoons are gorgeous but you will share the beach with other resort guests in season. If you want lively (Stone Town dinners, busier resort scenes, more dining variety) — Zanzibar. If you want quiet (private dhow, empty beaches, dugong waters) — Mozambique. See our
Mozambique honeymoon guide for sample itineraries and lodge tiers, or the
Bazaruto guide for the islands themselves.