Perl's used more widely than Python, if you look at job trends -- but then again, you have to consider that Perl 5 was more popular earlier, so there's a lot of entrenched usage. Python may or may not have more new projects written in it; the statistics are difficult to interpret.

You can get by knowing one or the other well. Perl's advantages to me are the CPAN, the tooling culture, the testing culture, and a very pragmatic approach to getting things done without the language or ecosystem dictating how.

Python's advantages are slightly cleaner defaults in Python 3 and the fact that all code looks basically the same. (I'm not sure I see that as an advantage, but other people do.)