There will always be the matter of opinion too. Sure you can measure 8x10 contact prints to smoke 35mm enlargements to the same print size.

Your eye may or may not appreciate the difference too. It's a matter of what you like. I'm in the camp of appreciating how the 35mm enlargement looks compared to the contact print, mainly because I dislike the baby skin smooth (lack of) texture in the print. I fully understand why others like the contact print better, and would hope for the same respect in return. It isn't right or wrong.

A question I find very important in this context is: "How much does it matter?"
After you look at what your needs are to express what you want to express, and how much your film format and resulting prints contribute to that, you will know whether you need to be shooting 8x10, or if you think enlargements from 35mm or 120 negatives will suffice.

My own reasoning is that enlargements up to 20x24 (or crops that correspond to the same level of magnification) look more than good enough from 35mm and 120 originals. I really never feel that a 4x5 negative of the same subject, with the same depth of field and view, would improve the photograph somehow. The grain would be smaller, tonal breaks from one gray tone to another would be less abrupt, and so on. But I find that it doesn't matter to me, and that sometimes I even prefer the grittier look.

At 8x10 print size I notice a pretty clear difference between a contact print and an enlargement. From 4x5 it might be more difficult. But from 120 and 35mm it's definitely evident. Which is better is subjective.