My experience with Unity is that - yes, it is more versatile engine, with great options for porting your game to different platforms.

3DGS seems to be a more powerful engine that can run a lot faster with more things going on.

This could be because I don't know enough about Unity, but I made a Unity version of one of my games "Anomalies" and it runs really slow if the object count goes a bit higher. 3DGS handles lots of moving objects really well and smooth (with limits of course).

I am still wrapping my brain around Object Oriented Programming, but I keep coming back to 3DGS because I know it well, and can get results faster.

I do think my next project will probably be in Unity though ... we'll see.