Moore was a great light heavyweight champion. Hopkins was a great middleweight champion, who was also a good light heavyweight champion. Therein lies your answer.
a lot depends on how old they are. given how one sided it is so far i'm taking hopkins to make moore second guess his punches and win on points in the fight with the lowest punch count in history.
Hopkins gets a taste of Moore's power and gets on his bike for the rest of the night. He makes it a stinker and Moore wins on points.
I'll never believe any champion lets an experienced fighter hang around for 12 rounds because he feels like showing off
Hopkins' (who fought Tarver) skill and guile see him to surviving 15 rounds and losing the decision to Moore.