For WW1, the reason I consider Allied and Central powers to be equivalent has more to do with the flaws of the Allies in that era than with the actions of the Central powers.
With WW2 and Axis/Allies, even though I’m not at all sure how to judge the relative behaviour of Stalin (Allied) vs Hitler (Axis) — there’s too much propaganda for me to filter though — the British and Americans were unambiguously more moral than the Axis powers.