Earlier quoted context omitted.
My joke was it takes a much larger team to get anything done in UE4 . I couldn't imagine solo dev on an Unreal Project .
We tried it for a hackathon and after a day or so we got some stuff going. Of course it's a monster engine, but you can learn it as a side project, then after a month you can start building something. I don't see why a solo dev couldn't handle it.
The available learning resources for Unity are much better than they are for UE4. I want to add X to my game, I Google it and find ether an asset or open source project within minutes .
For my current project I found a half dozen templates to start from. Everything in UDK was ether half done or abandoned.
Of course both , or even rolling your own , are fine.