Once, I listened what some people said on the Internet, and I tried Arch. I came back to Manjaro, but I learned a lot so I'm not unhappy with the experience.

However, to say that there's no reason to use it over Arch (I don't know about Endeavour, I never actually used it) is just wrong. Maybe you don't like the differences, but they are important and useful for someone like me. When I installed Arch, I needed to tinker it for hours before having something usable. I don't want to tinker, I want my OS to work, even if it means other people made choices for me, as long as I can revert them; that's what Manjaro offers. For example, I love GNOME, but only with some plugins, like dash to dock. When I installed Arch, GNOME made an update which broke a lot of plugins, included dash to dock; while Manjaro waited for dash to dock to work to push the new GNOME. Some issues may be pushed, but a lot of others aren't. I prefer to have one big update twice a month instead of having to update and tinker again my OS possibly every day.

Manjaro is far from perfect, no distro is, but for people like me, it works very well, and better than Arch.