Featured: a hard cap for one unit
A Featured banner is the only place where a specific SSR has a predictable ceiling: 60 pulls. If the featured unit is someone you will actually play, saving for that guarantee is the most efficient use of Astrogems in the game.
Standard Character: plan for the selector
The permanent character pool guarantees a random SSR every 60 pulls. That is useful, but it does not let you choose. The real value sits at 180 accumulated pulls, where you pick one SSR from the pool yourself, and again at 300 for a second pick. Pulling in small batches hoping for luck resets nothing — but it also gets you no closer to a selector than banking the same pulls would.
Standard Ability: complete a kit you already own
Ability shards unlock and level a character's signature moves. The pool has the same 60-pull SSR guarantee, a five-slot wishlist that biases drops toward your picks, and a selector at 150 pulls. It is a strong pool — for an account that already has the unit in question.