Would be a lot easier with New Testament or Book of Mormon, since the Old Testament is full of such atrocities, its hard to find a story that isn’t morally offensive. Its kind of like asking “what is your favorite Nazi story”, so perhaps you meant it as a challenge, if so I’ll give it a try.
* Child sacrifice - Judges 11:30-39, Jephthah burns his daughter alive as a sacrificial offering for God’s favor in killing the Ammonites
* Rape & Incest - Genesis 19:1-11. Lot, the only righteous man in Sodom, offers his virgin daughters to be gang raped by a crowd. The crowd turns him down and he impregnates his daughters himself in Genesis 19:30-38
* Concubine raped and dismembered - Judges 19:22-29, a mob demands to rape a godly master’s guest. The master offers his daughter and a concubine to them instead. They take the concubine and gang-rape her all night. The master finds her on his doorstep in the morning, cuts her into 12 pieces, and ships the pieces around the country. - WTF??
* A tribe slaughtered and their virgins raped for not showing up at roll call. Judges 21:1-23, the other Israelites kill them all except for the virgins, which they take for themselves. Still not happy, they hide in vineyards and pounce on dancing women from Shiloh to take them for themselves.
* God has 42 children mauled by bears for teasing Elisha, 2 Kings 2:23-24
* God kills a man for refusing to impregnate his brother’s widow Genesis 38:9-10
* God helps Samson kill 30 men because he lost a bet Judges 14:11-19
* Noah’s Flood - genocide and unrealistic
* Genocide after genocide after genocide, including killing men women and children, although occasionally keeping the virgin girls as sex slaves. Joshua 6:20-21 Jericho, Deuteronomy 2:32-35 Heshbon, Deuteronomy 3:3-7 Bashan, Numbers 31:7-18 Midianites, 1 Samuel 15:1-9 Amalekites
* Exodus 12:29, God slaughters all Egyptian firstborn children and cattle because their king was stubborn - thats just sick
* Chronicles 13:15-18, God helps the men of Judah kill 500,000 of their fellow Israelites
Its really difficult to find any good stories in the Old Testament, but I did find two I like.
* Balaam's Talking Donkey - Numbers 22:28 - Reminds me of the movie Shrek, also saw a version illustrated with Lego people which was amusing.
* Joseph - Genesis 39-45 - This story actually is more detailed/interesting than most, and in the end Joseph forgives his brothers, which is a much better moral story than most of the stories that are full of all sorts of violence. I’d pick this as the favorite.