Morning Star

What a whip does is tag. Hitting an enemy pulls your minions onto it and makes each of their hits land harder for as long as the mark holds. This one carries the strongest tag available at its stage, so the routine is to crack it across whatever you want dead and let the summons finish the job while you keep cracking.

It is long, and it barely loses anything on each additional enemy caught in the swing, which is not true of most whips. A Pumpkin Moon lane or a wave of Old One's Army enemies takes close to the full hit across the whole arc. That combination keeps it in the hotbar long after you have left the Dungeon behind. It also knocks things around harder than any other whip, which is occasionally a problem when you wanted a target to stay put.

Raw output between the two is close, and a melee speed build can push the Dark Harvest ahead because its swing accelerates as it keeps connecting. Morning Star wins whenever there is one thing you need dead, since the tag boost feeds straight into your minions and the crit bonus rides on top. Summon crit chances roll as separate events rather than adding together, so stacking them goes further than the raw percentages suggest.

Armored Bones in the hardmode Dungeon carry it and the rate is unkind. A proper farm with a Battle Potion and Water Candles running is the difference between one evening and a week of walking corridors.