What Wireframe/Prototyping Software is the Best?

As information architecture and user experience design become a more standard part of major web and interactive projects, there are a few software tools emerging as the gold standard. A good prototyping tool can dramatically speed up the process and boost the quality and fidelity of the wireframe/prototype itself. But a bad tool can slow you down and create frustration for you and the client. While you could create wireframes with a pencil and paper, choosing the right tool can dramatically enhance the final product, or burden your project with tedious repetitive edits or unsatisfactory prototypes at the end of…