I really do like how Tanjiro won through the bond from his family. Tanjiro deeply cares for Nezuko and wants to avenge the rest of his family as well. Using what he learned from his father combined with Nezuko's newly acquired Blood Demon Art to defeat Rui, who firmly believed that family bonds could be forged through anger and fear, adds some more emotional weight to the victory. The song and the ending theme with Tanjiro's family members were also quite nice.
If that's true, then it's unfortunate that the season is almost over(Black Clover seriously had 48 for their first season-_-).