John Stockton would like to have a word with you ;).
I'm not saying Stockton was necessarily the better offensive PG. However, I think the difference between the two on the offensive end is very small. Nash is the better scorer, while Stockton was the better passer; but overall, they were at about the same strength.
Also, Magic Johnson ca. 1988-1991 averaged 20PPG and 12APG with a .35 3FG%, so he might have a word in that discussion, too.
Nash is the best offensive PG of our time though, that's for sure.