Fedora repos + REMI + RPMFusion, and now Microsoft is developing software for RedHat, which is available for Fedora as well. You can also add repos for CentOS, OpenSuse ; and somehow Arch people like Fedora people, so aur repo also works perfect.
You can just dnf a window manager, like KDE, Bhodi, Pantheon etc., and then switch between them in Gnome Login. If you don't like gnome login, you can dnf another login manager... literally plug and play.
You cannot really customize gnome to look like other things, and gnome nautilus is still too simple, it does not have enough features. Also, there is no icon by default on Desktop, that bothers some people.