I always find this topic to be really interesting since there’s no objectively correct answer, and it tends to be something people have experience with.
Obviously, the best answer is “let the player pick”, but personally, I’m 100% in the inverted camp (both y and x axis, because apparently some maniacs only invert one). I have no idea where I picked up inverted controls, but I’ve favored them as long as I remember playing games, so I figure some early titles I played had inverted by default, which checks out since I played a lot of vehicle-based games.
For me, one of the worst experiences is realizing a game I really want to play only supports uninverted camera (or in the case of a couple, only supports inverted y), because it totally demolishes my ability to reasonably play the game with any degree of skill.
Standard unless there’s and flying involved, either in atmosphere or space, then I invert Y. Can’t imagine ever inverting X, that just blows my kind. Been playing since before WASD was a thing, so I’ve seen most implementations I guess.
To picture both x and y inverted, imagine the camera as a separate object that you move around to obtain the point of view. Or to simplify it down to 2d, imagine the camera as looking through a circle. If you want to look at one quadrant, you need to position the camera in the opposite one. So to see positive x, positive y as the target of your view, the camera looks through the origin point from the negative x, negative y quadrant.
I guess I always have it my head I’m the object I’m controlling rather than the camera following, so my brain defaults to more direct control? I do tend to favour “in-cockpit” / first person view.