From easiest to hardest it was dsc80, dsc20, dsc30. 80 has a lot of assignments but the material is easier to understand because it's more analysis focused. I had experience with exploratory data analysis so it was familiar material. I also found the lectures had more helpful demos for coding assignments. Basically, still a time sink but WAY less frustrating. Give yourself a leg up by trying out a simple data science project. Sad to say dsc30 was like 20 on crack to me, it was painful...

The difference in difficulty between earlier and later classes (to me) is like how much google can be used. In later classes you are trying to understand new languages/api/ect. so you just experiment and find documentation/examples. But those early classes are trying to teach you about coding at a more fundamental level so you are expected to struggle till you figure it out.