Not as clear as it seems. I have played against both of them on a few occasions.
Allison Fisher has accumulated many more major nine ball titles than Jean and is, at least, Jean's equal in nine ball. If anything would have tipped the scale in Jean's faor, however, it would have been her break, which was comparable to the top men, but my inclination is to procliam Allison the greatest woman nine-baller ever.
In 14.1, the only other player in the conversation for best ever is Ruth McGuiness, who toured with Greenleaf. Ruth had a high run, if memory serves, in the 130's, which is the same as Jean. Jasmin Ouschan and Jeanette Lee are next in the pecking order and are not behind Jean and Ruth, and then comes the great Dorothy Wise.
All around, however, Jean is, without question, the greatest ever. She's a great player and a great lady, too.