File Formats for Conversion to XAML

As WPF application development continues to pick up steam, it's becoming more and more important to consider which file formats make the most sense for conversion to XAML. Just based on discussions I've had with many of you regarding my Illustrator export plug-in, I know that there are other formats out there that—due to lack of tool support—are very difficult or next-to-impossible to convert to XAML.

So, I'd like to identify a list of "top x" file formats that would help ease the pain for both WPF designers and developers. What tool does your company use to create 2D or 3D content? What file format(s) does it make the most sense to convert? If you don't have an opinion (possibly because you don't work with those tools), please forward this to your design staff. I'm very interested in feedback.