* Fedora and Ubuntu are more aggressive about compiling security features into the packaged binaries, whilst Debian considers package build flags to be the decision of individual maintainers, so coverage is more piece-meal.
* Fedora ships SELinux enabled. I believe that current versions of Android is the only popular non-Red Hat Linux-based system that does that. The common compliant about RH's SELinux implementation is that it is so restrictive about system integrity that it blocks actual system administrators from doing routine tasks unless they remember to change the appropriate SELinux policy settings first.
* Fedora 25 now uses a Wayland implementation for managing graphics by default, rather than X, so that the security issues of X don't apply.
* Fedora 24+ includes Flatpak, so that there is a system for sandboxed applications. Fedora 25 provides the UI integration for non-technical users to run Flatpak packages (once developers build them).
* The RPM/DNF package management system is more stringent about checking downloaded packages than APT.
I am also a proud and happy Linux user going on about 10 years now, and what's great is that I know all the knowledge I've acquired will still be relevant many decades into the future -- not sure the same can be said of Windows or MacOS.
I also often see it brought up that Fedora uses SELinux by default.