For various reasons we are required to add feeds to our product. The main reason is to be able to say to potential buyers that "yes, we have feeds". We do not actually expect the feature to be used that much. Ideally we would like to provide both RSS and Atom feeds. However, at the moment we are severely pressed for time and are forced to select just one of these. Should we use Atom or RSS? Feature-wise we are fine with either, so I am only looking for information about the popularity and support for the various formats. Are there many feed readers out there without Atom support?
The reason we only want to implement one format is not related to generating the actual feeds. That in itself will not be very time consuming. It is more of a UI problem. If we implement both Atom and RSS, we need to present the user with a UI where he/she can select between the different formats. For usability purposes we would also need help texts, tooltips etc. to make sure that the user can understand the different options. And since our product is localized into multiple languages all of the above would need to be translated, and someone has to pay for that. It all adds up and becomes a lot more work. If we settle on a single format we only need one button with a tooltip pointing to an .aspx with the feed. Besides, it is not my decision anyway. :) Someone above me has already decided that this functionality will be implemented for this release.