Chishiro, the Shattered Blade Chishiro, the Shattered Blade gives you a strong incentive to play auras and equipment, and to have modified creatures
Aerith Gainsborough is more expensive, but the built-in lifelink means you probably dont need to worry about where your lifegain comes from
It has been cheated into play by decks using Indomitable Creativity alongside a haste-giver in Pioneer and Modern and even abused for its high mana value in the "Grishoalbrand" combo deck
Examples of non-rotating formats include Pioneer, Modern, and Commander.
Obviously since I didn't finish yet, there will be more stories to come
Control and midrange decks appreciate how it thins the deck slightly while guaranteeing future land drops, and Commander players like having a low-opportunity-cost way to fetch whatever basic theyre missing