In general, python is a more "regular" language with less unusual cases - so it tends to show up a bit more often in traditional programming 101 courses. It also promotes readability by making indentation a part of the language syntax.

That said, Javascript is readily available (a runtime in your browser), so no additional installation steps are necessarily required to start. Javascript also follows C syntax patterns which also appear in a number of other languages whereas python is a bit unusual in the way it distinguishes code blocks (using indentation).

Either will work, I think that python is a bit more straightforward for your first few programs.