Spicific Impulse is the basic factor from which all else derives. The performance of a rocket can be described in terms of Specific Impulse. From Specific Impulse the entire rocket, staging included, can be designed in a couple of minutes. Delta-vee is merely the inverse of payload; 100 tons to orbit would be as meaningful a criterion as delta-vee--it tells you nothing of the size of the rocket or how many stages would be required.
Thank you for explaining that to me.