I assume by saddle sores you mean small lumps on the perineum which can be unbearably sore to ride on, rather than just chaffing.
I developed this problem for the first time a few years ago, and after unsuccessfully trying a variety of different shorts, was advised by a forum member to invest in a
Selle Anatomica Titanico saddle.
This not only cured the problem but the Titanico has turned out to be by far the most comfortable saddle that I have ever had. Unfortunately it is also the most expensive, but overall it is probably one of the best investments I have ever made in terms of cycling comfort.
The
Brooks Imperial is similar in concept to the Titanico. but I have not tried it so can't confirm whether it prevents saddle sores.
By the way I found that once you get a bad saddle sore the only way to get rid of it is to have a break from riding for a couple of weeks.