Board Thread:Questions and Answers/@comment-33071096-20180902164828/@comment-27047700-20180915181843

Lucy (Nice STR/DEX/QCK boost which allows for diversity), Luffy/Ace dual unit (Huge boost for Free-Spirited units), Dark King Rayleigh Old Man Watching Over the New Age (A captain that supports all types and classes, with a nice boost), and Heavenly Demon Doflamingo Leader of the Bird Cage (Nice usage on Driven teams including the huge boost) are top tier captains right now. All of these are sugo-fest exclusive units. So I'd recommend starting during a sugo-fest such as the Gear 4th sugo-fest coming up in a couple months. You might be able to reroll and get the new Gear 4th unit (big rainbow boost) which is also very useful.