The full texts of these abilities are "At the beginning of the monarch's end step, that player draws a card" and "Whenever a creature deals combat damage to the monarch, its controller becomes the monarch." If the triggered ability that causes the monarch to draw a card goes on the stack and a different player becomes the monarch before that ability resolves, the first player will still draw the card
While it is ultimately arbitrary, here is what I was considering when ranking the cards: Use Scenario: I took into consideration where the cards will be used, for example Commander deck cards are considered in that sense, while uncommons in the main set had more thought put into limited usage
Limited-time Disney Lorcana card features stunning Moana 2 artwork in silver foil
Sephrioth, Fabled SOLDIER's second ability mirrors that of Blood Artist, a common inclusion in sacrifice decks
Starscourge At the beginning of combat on your turn, exile up to one target creature card from a graveyard
Since Kefka, Ruler of Ruin has flying and is pretty tough, you can also likely attack with it to draw some extra cards