For a new user, the most important things are usually a familiar feeling desktop environment, comprehensive default hardware support, and plenty of documentation in case you need it. The most important anti-things are needing to learn a bunch of new concepts right away and needing to use the command line, and experimental things that are know to break regularly.

Since you’re a Mac user, I would suggest KDE over Gnome for a desktop environment. Even though the default Gnome application bar looks very Mac-like and the default bar on KDE looks very windows-like, the rest of the KDE desktop feels much more Mac-like.

For the rest, you will want to use a common distro with a wide user base and a long history targeted at desktop users.

For those reasons, I would suggest either Kubuntu, or Fedora KDE.