Why an iMovie alternative cannot honestly argue price or privacy
Most comparisons on this site turn on one of two things: the footage being uploaded, or the export being watermarked. Neither applies here. iMovie processes on the device, costs nothing, and marks nothing. Any page telling you otherwise is not describing iMovie.
So the only question left is what happens to your time. iMovie hands you a clean, simple editor and expects you to drive it. That is a fair deal for a holiday video and a poor one if you publish weekly.