This is one of my pain points, and one time I googled and got the real answer (which is why it's such a pain point).

That answer is "It depends on the context"

> The reason the "ours" and "theirs" notions get swapped around during rebase is that rebase works by doing a series of cherry-picks, into an anonymous branch (detached HEAD mode). The target branch is the anonymous branch, and the merge-from branch is your original (pre-rebase) branch: so "--ours" means the anonymous one rebase is building while "--theirs" means "our branch being rebased".[0]

[0] https://stackoverflow.com/questions/25576415/what-is-the-pre...