The way I structure my commits, it is usually (but not always) easier and more reliable for me to replay my commits one at a time on top of the main branch and see how each relatively small change needs to be adapted in isolation–running the full test suite at each step to verify that my changes were correct–than to be presented with a slew of changes all at once that result from marrying all of my changes with all of the changes made to the main branch at once. So I generally start by attempting a rebase and fall back to a merge if that ends up creating more problems than it solves.
The way I structure my commits, it is usually (but not always) easier and more reliable for me to replay my commits one at a time on top of the main branch and see how each relatively small change needs to be adapted in isolation–running the full test suite at each step to verify that my changes were correct–than to be presented with a slew of changes all at once that result from marrying all of my changes with all of the changes made to the main branch at once. So I generally start by attempting a rebase and fall back to a merge if that ends up creating more problems than it solves.