I am thinking of using either RSS or Atom in my project, but also "enhancing" the feed with some of my own special attributes specifically used by my project.
So I have two questions:
1) Which is most used of RSS and Atom on the web and by the big sites?
2) Which is most suitable to be build from by adding my own tags?
Update:
So RSS is most used, but I should pick Atom since I need to make my own tweaks on a feed? If RSS is more popular, why not pick that? Why didn't Google pick that?