If you are doing it for personal growth and learning, then Perl 6. It is an interesting language that cleanly supports many major programming paradigms including functional, imperative and object oriented and, most probably, others. Additionally, it has many nifty features built in such as concurrency, grammars and rationals. Aside from that, it is also fun to use and has a great community.

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.

Perl6 is mostly complete. Even though it has been getting significant weekly performance improvements (they have a weekly summary of these things), it still has a long way to go. It has a lot of really cool things such as simple to use concurrency, grammars, gradual typing...etc. It is a big language, but not super hard to learn. A bunch of books have been released on it in the past two years. Perl5 is used by companies now. Some are choosing to write new software in it, but there is a lot of legacy apps.

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.

Depends on what you're looking for:

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 [1]). 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).

[1] https://gist.github.com/cygx/9c94eefdf6300f726bc698655555d73...

Perl6 has grammars: https://docs.perl6.org/language/grammar_tutorial (recursive regex with sane syntax), which are much better than plain regex in many cases. Otherwise modern Perl5 is much more practical.

If you want to get paid for doing it, Perl 5. If you're just mucking about with personal projects, Perl 6.

Perl 5 and Perl 6 are two different beasts. Perl 5 is closer in spirit to Awk.