Purchase doesn't have the option to choose the next step. Right now the only action that can follow a purchase action is a schedule action. However, you can cancel the schedule action after completing the purchase action, which will automatically add a review action (and you get the same result). We added these options to the Quote action recently as well. If we want the Purchase action to have similar capability, it's probably worth to discuss if all actions should have a way to add "next steps".