Q: Which one should I choose?
A: Hindenburg is easier to use and is the industry-standard for podcasting. It is not free, however. Audacity is free and open source, but less intuitive and more complex. If you need to edit on your personal computer and don’t want to spend money for Hindenburg, use Audacity. If you plan to work in the podcasting industry, it is worth it to learn Hindenburg.
Reaper is available for free, but with a suggested donation. It is more complicated than Audacity; you should use it if you enjoy working with audio and want to develop very strong skills for the audio industry.