I don't know where to set my story.

I want to start my first worldbuilding that I have planned to take place in the space, but I don't know what of those options to choose. One of my options is to set the story in our solar system (with some moons and planets terraformed), but the problem is the laws of science and physics, I don't want follow some of them. Because I want all planets and moons of our Solar System have the same gravity of Earth, and the moons (of Jupiter, Saturn, Uranus and Neptune) were not tidally locked. And I wouldn't know how to explain that.

The other option is create a fictional galaxy, but a galaxy is huge. Also I think the work would be more difficult than in our Solar System, but there would be some creative freedom.

I haven't written anything about my worldbuilding yet. I just have some ideas in my head. The story that I want to make is about a police-like organization in the space.
So, which option is better to use?

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By the way, sorry for my English.