Perl is really great at text processing. Pretty much any kind. A lot of folks dislike first-class regexes, but if they're magic in a lot of contexts like this.

My second remaining use is experimental coding. It is probably about familiarity and experience (I've been writing perl since Perl 4), but I find it to be the most fluid, most "fun" language for noodling around and trying out ideas.

I use Python for things other people will have to work on, because it is the current popular kid, so most folks have at least seen it. Not because I especially like it - the GIL is still a performance killer, purity of essence arguments keep obviously useful things (like case statements) out, and (as I'm sure will be demonstrated shortly) there are always annoying people around to condescendingly tell you why you're wrong to want things like case statements.