Both are great and work the same. Strawberry Perl is known for being able to build XS modules, but you can do that with ActivePerl too if you just install the Visual Studio SDK (or the free Express version).
For that matter, if you have access to Visual Studio, the best you can do is to build Perl from source (it's pretty easy if you read the README) and keep building your modules with the same compiler. That's actually a better idea than having a mixture of compiler/modules.
One thing you have to consider if using ActiveState: If you install it on a server facing the Internet, then you are required to buy a Business license ($1000/year/server as noted by Ron Warshawsky). It doesn't mean it won't work; it's only a matter of being a requirement in the EULA. Many people don't know this and have it installed on Internet-facing servers without buying the corresponding license.
