This question would throw me for a loop because I don't have anything I think of as my least favorite language.
I could pretend that Python was my favorite language, but that's more that I'm comfortable with it than any sort of actual feeling that I should prefer it over others. That is, I use it out of inertia and familiarity, not out of some sense that I've found something.
See, but that's a reasonable answer. I might take that and pivot to like "if you had to design an ideal language, drawing from the strengths of the ones you've worked with, what would you think most important?". The idea is to get you talking about things you've worked with to show familiarity and critical thought about your tools.
I could pretend that Python was my favorite language, but that's more that I'm comfortable with it than any sort of actual feeling that I should prefer it over others. That is, I use it out of inertia and familiarity, not out of some sense that I've found something.