... i think both.
i understand Atemi as ability to strike precisely at a vulnerable point, while ki is focus on power of the strike.
used together they are a powerful & a quick way of defeating human opponent, with or without harming, but both require a lot of skill & training.
i also think that for someone with 2nd Dan aspirations, such as i ... it's worthwhile to focus more on Atemi over Ki.
... for Atemi is also Ki.
... i've experienced a truth & power of these words during one of Jiu-Jutsu lessons i had, when Sensei struck lightly at a point on my neck, i lost consciousness (without falling to ground) for a short while.
it's a very clear truth for me that even a slight touch can turn someone unconscious, rendering him or her unable to fight.
i got 'a homework' from this Sensei to study biological anatomy of a human being, as a part of Martial Arts practice ... i wish i had more time & focus for that, as far as my priorities allow.
i think i should study chakras (energy centers, nervous centers) mostly, got intuition that it's my way anyway.
i think both Atemi & Ki fall well with Karate Way, nevertheless.
i think both Atemi & Ki fall well within the style i am trying to develop anyway, as well.