Except this would be misnamed then, since a counterattak is an attack you would make to counter an attack against you, which has no bearing upon an opponent drinking a potion or casting a teleport spell.
*****
As for me, Opportunity Attack is my favorite. I like to remove prepositions from names when I can, so this is preferable to Attack of Opportunity for that reason. And it still leaves a reference back to 3.x where the concept was born (at least born in D&D).