I used pure Arch for a few last years as a main system on my laptop (installed and configured in console manually, so I'm not a full newbie), and have used other Linux distributives before that also as a main system. Arch is fine, but unfortunately I recently realized that I need more stability and that's why I switched to Manjaro. I'm still not sure, but seems they do some tests and polishing taking Arch packages, making sure core components work well, etc.
PS I installed Manjaro not using GUI installer, since it doesn't support disk encryption well enough, and I don't use GRUB (default Manjaro boot loader), but refind.
I love Arch and I've installed it on plenty of machines, but I've already grasped what little pedagogical value the install procedure contained and now mostly want to have the computer automate that process while I work on other things. Hence I installed Manjaro on my wife's laptop last night.
PS I installed Manjaro not using GUI installer, since it doesn't support disk encryption well enough, and I don't use GRUB (default Manjaro boot loader), but refind.