Biggest dog in the kennel as far as I'm concerned, at least after the first century. A model of humility, he could see the Church had become corrupted by wealth and power, but used his gifts to lead by example rather than inveighing or rebelling.
One of my favorite stories is about St. Francis going to dinner at the Archbishop's palace. The custom at the time was for everyone to bring something for the meal from their kitchens or cellars, and they all vied to bring the most sumptuous food or wine. Francis, who lived on the handouts he could beg from others, excused himself from the meal to beg bread from the neighbors, and then returned to the dinner with his offering.
I told the story recently to show how simple acts can have long range consequences. Francis inspired thousands of Franciscan monks to honor their vows of poverty. It was not heard in that way -- my poor storytelling, I'm afraid. But the Archbishop got the point, and so did generations of monks.
If you ever visit my mom, you'll see a St. Francis statue in her backyard that belonged to her sister-in-law, Esther.