Must run desktop(in order to run Atom-ide); not a fan of apt; which rpm dist is best for this usage?

CentOS or Fedora would both be great candidates for this use case! They're both free and open source, are supported by their respective communities, and should be able to handle running Atom IDE in a desktop environment.

Fedora is the experimental option of the two. It has a relatively short life cycle, with each version usually being supported for around 13 months. Fedora also frequently releases updated packages, which could potentially be less stable than what you would get with CentOS. If you're interested in the cutting edge of Linux development, however, Fedora might be for you!

CentOS is essentially the free and open source version of RHEL. Its life cycle is much longer than Fedora, and there is a comfortable stability in how CentOS runs (and how long it will be supported for). If you'd prefer to prioritize stability and long-term support over fancy new packages, CentOS may be your best bet.

You may find that you prefer a distro outside of these two! In the end, it's all about user preference. That's the beauty of Linux!