As Plaguecrafter's ability resolves, first the player whose turn it is chooses a creature or planeswalker they control, then each other player in turn order does the same, knowing the choices made before them. Then all the chosen permanents are sacrificed at the same time. Next, each player in the same order who couldn't sacrifice a permanent chooses a card in hand without revealing it, then the chosen cards are discarded at the same time.

Each player chooses a permanent to sacrifice from among the creatures and planeswalkers they control. You don't choose which type of permanent any other player has to sacrifice.

Plaguecrafter can be the creature its controller sacrifices for its own ability.