Both would be acceptable if you are answering in that monosyllabic way. And I agreed with NeyF, he hit the nail on the head on that one.
Now the rule of thumb as how to use one or the other, if the pronoun is the subject of the action/verb then we should use "me", e.g.:
The one who likes me or the one I like. At this point, her head is saying one thing, and her heart another.
In more pragmatic ways, me would come after the verb, and I before the verb.
Anyway, with questions like that and answering in such terse way both would be acceptable (at least in a more informal situation), why is that? Certainly because the one answering may think of something like "it´s me it´s me that like chocolate.", but then many would think "I, I like chocolate".
Be aware, though, that this happens with the pair "I/me". If we were asked the same question and we knew other people around is the one that likes chocolate, fat chances that we would answer "he/she" instead of "him/her".