To be fair, all three can probably do what you're asking for, in building a desktop application. So the real question comes as which flavor of language do you want to write. The only language of the three I can't speak on is Ruby, as I haven't used it.

Python is a "scripting language", but by that token technically so is Javascript. It's an immensely popular language due to its simple syntax, yet complex features as you get better with it. Python can build large-ish applications: web apps, desktop apps, terminal apps, and yes also of course AI, bulk data processing, etc. For GUI applications, I've personally used pyqt (4? 5? 6?)

Much of the same can be said for Javascript. As you said, there are "negative opinions" about JS, but everyone has their opinions (most factually-based) on the goods and bads of languages (although, yes, JS does get more negative opinions than others). Yet, Javascript is still a widely used language, and you'll probably end up needing learning it anyway if you decide to go into web development.

What I personally suggest is this:

• See the learn x in y minutes pages for Python, Javascript, and Ruby. Make sense of the quick-tour of the languages.
• Make a simple project using each of the three languages. Something that just reads something from STDIN, does some work, prints stuff, as an example. This helps you get to know the basics of the syntax, tooling, and quirks of a language, and helps you narrow down which language you'd like to be working further with.
• Pick one of the languages you're leaning in favor of and go build your application. If you come to a point where you feel like the language you choose is no longer suitable for what you wanted to do, you can always retry with another language, and then you will know at least a fair part of more than one language.