Suggestions for simulator (Gazebo or Vrep)

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With a quick disclaimer that I don't know much about Vrep, I would say that its hard to beat the community around Gazebo. This will tend to make it easier to find answers to questions if you get stuck, and you will be more likely, in my mind, to find examples of the types of applications you are interested in.

I recently used Gazebo to simulate aerial robots running ORB SLAM2 using PX4 and ROS1, and didn't have too many issues on the simulator side of things.

For which simulator is "best", that will really depend on your definition of best. Are you interested in realistic physics? Collisions? Rendering? Do you want to run faster than real-time? Different sims will have different strengths and weaknesses and there are some comparison papers floating around out there.

For aerial robot simulation, my understanding is that many in academia have been moving towards dedicated drone simulation packages with more powerful underlying graphics libraries (e.g. Air Sim and Flightmare). I am unaware of these platforms also being able to simulate ground robots, though I admittedly haven't looked much into it.

EDIT: This recent publication offers a quite detailed comparison of different simulators for different purposes.