I took a "Computer Algebra" class in undergrad which was taught entirely in Mathematica. It was a lot of work to convert everything (and the instructor would jokingly refer to me as "sage guy") but I got an awful lot out of using Sage instead. What keeps me from using sage nowadays is that I have a great jupyter workflow, and last time I used Sage it was just a worse version of that with better symbolic support.
Just went to sagemath.org to check it out. The link to the changelog is broken.
My editor was concerned about the two names, Sage and SageMath. As far as I could tell they're just synonyms, but do you have any guidance about which is to be used when?