Lately with work, I've been busy in some old school .NET 2.0. Until you work with something different, you never really realize how easy it is to do development in Perl. My top three reasons why I enjoy Perl over other languages:
1. Built-in complex data structures. I don't need to invoke, import, or compile any additional dependencies to gain lists, arrays, and associative arrays. This is big. Most Perl regulars don't appreciate their hashes and arrays until they are once or twice removed from the core. .NET has these data structures of course, but I have to be "using" the Collections namespace, instanstiate full blown objects, and deal with a lack of literal construct for them.
2. Transparency. Much like mst does and recommends, I, too, read the source code of modules before I use them to make sure they are inline with what I could consider good coding practices. This means when I have a problem or a bug with a module, the source to that module is really close at hand. This goes the same for what modules are considered "Core." If I believe there is a problem with how I am using a module, and the documentation is ambiguous, I can always pop open the .pm and figure out wtf is going on. This is much harder to do with the class library with .NET. Sure you can install a reflector and look at generated-from-the-bytecode source, but you lose quite bit of information doing that.
3. Platform choice. When we do Perl projects at work, we cover a pretty good spectrum of platforms. Some develop on OSX, I develop on Debian, and we've typically deployed to FreeBSD. Our codebase is typically git friendly, dependencies easily installed with cpanm. With .NET, I pretty much /have/ to develop on windows and deploy on windows and typically use something like svn, or TFS as a source code repository. Mono apologists need not comment. Oh sure you could whip out the cruisecontrol.NET and write your own pull scripts to pull shit out of git (with msysgit), but good luck getting that to fly with any customer that is in love with centralized source repositories and has a vested interest in maintaining them (TFS licenses aren't cheap). So what does that mean for me? It means dealing with the headache of doing development inside of a VM since I do not run windows on my machine for security and performance reasons.
Overall I prefer the development of projects in my beloved Perl. It doesn't mean I can't do development in other languages, I have bills to pay after all. It just means that I find the .NET environment to be rather limited and extremely monolithic. And good luck doing anything outside of the status quo, or poking at APIs that are rarely used. Down that path lies dragons.