If you know C++ already, Unreal is a much more natural starting point than either Unity or Godot.

Unreal is what gets used in many AAA shops - it’s not a monopoly by any means but it is the most common off-the-shelf engine in the industry. Unity’s main edge is that it’s easy to learn but if you are comfortable in C++ then there’s no real benefit to Unity.

Godot uses GDScript, which is a custom scripting language that’s meant to be easy to learn. It’s FOSS so you don’t need to worry about being screwed over - but it’s a lot less mature than something like Unreal which can ship on everything you can think of.