Hi Mary.
I certainly am no expert about cannolis; I've only made them once, using premade shells. I do love to eat them, though. From what I know about making them, the best ricotta to use would be the fresh-made kind that you can purchase at an Italian speciality deli market. This is a drier cheese product than that which is sold in tubs at grocery stores. It's cut into blocks after it's made, stored in brine until it's sold, and stays fresh for only about a week after it's made because it contains no preser vatives. It contains less liquid (whey) than tub products, so it's better for cannoli filling... It doesn't weep.

If you can't get a hold of fresh, genuine Italian ricotta, you can make do with the "tub" style if you drain it well first. Line a colander with cheesecloth, set the colander over a bowl, put the cheese into the lined colander, and let it drain overnight in the refrigerator before using it in your filling.

Hope that helped.