Some might reign supreme for a while until another creature is released to take the spotlight
My first instinct is to throw it into a Samurai and/or Warrior deck and combo it with Raiyuu, Storms Edge, but Commander has a lot of potential ways to keep extending a turn with more phases, and any devoted red player should consider having it in their deck
One of those is Plaguebearer, which sees play as a sideboard option in mono-black attrition decks
These cards are valuable because of scarcity, historical importance, condition, and collector demand
The war may be the same, but the battlefield is always new with Commanders Inquisitor Greyfax and Marneus Calgar. For a typical Magic design, I would have expected Celestine, the Living Saint to be yet another powerful legendary Angel, so I appreciate having it as a Human Warrior instead