Following up on this answer.
The answer seems to conclude that one way that we measure happiness is by the saying of Hallel and it lists the days on which we say the whole of hallel. But we do not say the whole Hallel on the final 6 days of Pesach which would seem to elevate Chanukah (a rabbinic institution) over Pesach, a biblical salvation. Why is the rabbinic holiday (on which many of the enemy died) "happier" than the biblical existential event?
I understand that there are other reasons or thinking explaining why we don't say the whole of Hallel on the 6 days of Pesach but they seem to revolve around the Musaf (as compared to the days of Sukkot) but Chanukah has no Musaf attached to it so I don't understand why it would be elevated (to a position higher than Rosh Chodesh also) via that logic either.