I hear constantly that Manjaro is a terribly managed distro that also gives a false promise of being more stable, because while they hold back updates for 2 weeks, they never actually patch packages if there is a bug found. They just release that bugged updates 2 weeks later, so it's waiting for nothing. I didn't look too much more into it, but I didn't need much of an excuse to not go from Arch to Arch+2-weeks-delay.
As for PopOS, it's a smaller distro than Fedora in terms of popularity. That's fine if it brings something I like to the table, but by default I'm gonna try out more popular distros before trying the smaller ones, so I tried Fedora before I got to PopOS and it's damn near perfect, so I never felt the need to try PopOS.
My memory is a little hazy on how exactly the trip went, but I think it was something like: Arch --> Debian Unstable --> Opensuse --> Fedora