As someone who tried both, I think Endevour is better.
1.It's more bleeding edge.
2. It's as close to vanilla Arch as you can get with a gui installer.
3. The dev team seems to be more compitent then the Manjaro team (i.e: shit doesn't break because someone pushed a WIP package).
4. Better community support (I mean, it's literally just Arch with a fancy installer).
They're both fairly easy to install. And it's fairly easy to switch between the two.