If all else is equal, I would select the lighter frame. This is not alway obvious. Last year I restored a 1985 Merida with alloy seatpost, alloy cranks, and one alloy front rim. The frame was chrome-moly steel. This year I restored a 1974 Peugeot with steel seatpost, steel cranks, and all steel rims. The frame was carbon steel.

The Peugeot weighs 28 lbs. vs 29 lbs. for the Merida. The alloy parts should make the components 1-2 lbs lighter for the Merida which suggests the real difference in weight between the frames is 2-3 lbs.