For what it's worth, when I've had to use perl on windows, I've used strawberry perl, without any problems. If it's good enough for
Larry Wall, it's good enough for me, and I've found this to be true in practice.
For my money, strawberry perl is closer to *nix perl, and cpan(m) has never given me any problems there. While I don't have a lot of experience with activestate perl (and I trust that I will be quickly corrected if I'm wrong), the ppm of activestate occasionally doesn't implement cpan modules as well or as completely as strawberry perl. But then again, that's just occasionally.
On balance, strawberry perl gets my vote.