If you are doing it for immediate application in a job or wish to acquire a skill you think might be required in a job then the answer is probably Perl 5. Despite the noise about Perl, it is still used a lot in many industries for flow control and inter-tool format conversion as well as many other applications. Many, many people understand perl and use it for rapid development of automation tools. I can tell you for a fact that it is pervasive in the semiconductor industry and is practically a job requirement, there.
Remember that they are two different languages with some similarities. Perl6 has really good support for making big apps I would say as it has really good OO support out of the box in addition to making FP concepts easy too. Perl5 has atrocious support baked in, but they have the excellent libraries that everyone uses to give them world class support for OO. Still, it feels more natural in Perl6.
On another note, Groovy is another great and fast language that runs on the JVM and works very well in the scripting space with a lot of DSLs for GUI, XML, DB...cool stuff.
But the same versioning issue exists for Apache Groovy (2 or 3 ?) that exists for Perl (5 or 6 ?). The Groovy PMC seem to be handling the issue, though, by slowing down the development of Groovy 3 to a crawl so it won't ever ship.
Oh, and calling Groovy "fast" is a bit of a stretch. It hardly matters anyway because scripting for classes written in Java doesn't need "fast".
In many ways, p6 is the superior language. But as an AWK competitor specifically, p5 might be the better choice for performance reasons alone (while p6 has been improving, as far as regex performance goes, it just isn't there yet ). You might even be able to write tighter code in p5 (for one, p6 regexes return objects, not strings, so in cases where you actually want the latter, you'll have to throw in boilerplate).