Thirteen years ago, some podcast readers coped with RSS but not Atom, but everything else coped with both just fine. Since then, I think the podcast situation improved so that everything supports Atom; but it’s very difficult to find any information at all about feeds after 2007: the problems were solved, and so no one talks about it.
Atom is technically superior to RSS, most concretely in how it specifies the format of fields like title and content, whether they’re plain text or HTML. This means that I can use things like <em> and <code> in my blog post titles and have it work (clients will either display the HTML unaltered, sanitise it, or strip tags, leaving the correct text), and have blog post titles with text like <_>::v::<_> (real example!) not get mangled horrifically.
Atom is technically superior to RSS, most concretely in how it specifies the format of fields like title and content, whether they’re plain text or HTML. This means that I can use things like <em> and <code> in my blog post titles and have it work (clients will either display the HTML unaltered, sanitise it, or strip tags, leaving the correct text), and have blog post titles with text like <_>::v::<_> (real example!) not get mangled horrifically.
I do not recommend that anything use RSS now.