I am on a very tight budget and have taken only 2. The first was Fast and Flexible Log Cabins---very very good.
My favorite was Re-piecing The Past-Civil War Blocks by Kaye England. I used red white and blue fabric. This was an excellent class if you want your piecing skills to improve. The blocks get progressively harder. She shows a couple of different ways to make them. I did not put it together they way she showed and just made it a sampler type quilt.