I'm curious, because I haven't seen much discussion on this point: Ignoring that it is called Perl 6 and has it's lineage in a well-known language called Perl 5, what are some of its advantages over some of the other languages it will be considered alongside?
If I'm starting a new project, and I'm familiar with a bunch of other languages (including, but not limited to, Perl 5), what should draw me to Perl 6?
At this point Perl 6 is new enough that the use cases is excels at may not be well defined.
If you want to learn something new, and not be hampered by a feature in some other language not being supported (at this point the main feature is that it basically has all the features of all the languages), then trying out Perl 6 may be worth while. If nothing else, you've prototyped your project, found out what programming paradigms make sense and work well for your use case, and can switch to another language that offers that which achieves some other unmet goal of yours.
So, I guess that's a possible use case. Prototyping where you aren't sure what language features would be really useful and provide benefit later. Channels? Threads? Async? Promises? Lazy lists? Operator overloading? Roles? Grammars?
If I'm starting a new project, and I'm familiar with a bunch of other languages (including, but not limited to, Perl 5), what should draw me to Perl 6?