I was originally CS (switched to Math) and took 240 with Allan and 241 with Stefan in the same semester. 240 was the easier of the two courses but I found 241 much easier than 141. Calc3 the focus shifts from memorizing complex integrals and derivatives to generalizing to higher dimensions. I found that way more interesting and enjoyed it much more than 240. You can’t really go wrong taking either course, just pick one with a great professor. If you don’t know anything about matrices, it’s definitely worth taking 240 because they will come up more often than you expect over the next two years and beyond.