Which online college mathematics course?

Hi!

Just as the title says, I am trying to decide on an accredited college mathematics course to take online as a math class this year. I am a senior in high school, I have taken AP Calculus BC and AP Statistics and I have independent studied to a solid background in both linear algebra and multivariate calculus.

Looking at Johns Hopkins Center for Talented Youth (https://cty.jhu.edu/ctyonline/courses/mathematics/#College_Level) under college-level courses, I see four potential options: Differential Equations, Intro to Abstract Algebra, Intro to Real Analysis, or Intro to Complex Analysis.

I had been planning to study differential equations for a while before the option to take a different course arose. Thus, I am already familiar with some of the basics. But, I’d like to take the hardest course which I can handle. Complex analysis, in particular, seems to be an especially intriguing subject. Is real analysis a necessary requisite?

Thanks for reading, I’d appreciate any insight.

Ordinary diff eq was fun. Can’t comment on the rest of them. If you have a future major in mind check out what math courses you might need for that major.