MOV vs MP4
MOV (QuickTime) and MP4 are close relatives — MP4 was standardised from Apple’s QuickTime file format — and both can carry the same H.264 video. The practical difference is software expectations: Apple apps and many editing tools treat .mov as their native format, while web platforms and social networks prefer .mp4. Pick MOV for editing timelines and Keynote; pick GIF to MP4 for sharing online.
Because video has no transparency, transparent GIF pixels are filled with the background colour. To keep transparency in an Apple-friendly still, export a frame with GIF to PNG instead.
Using GIFs in iMovie, Keynote and Final Cut
iMovie and Final Cut Pro don’t animate imported GIFs reliably, but they handle MOV perfectly. Convert with enough repeats to cover the clip length you need. For an iPhone Live Photo instead, see GIF to Live Photo, and to add sound use Add Music to GIF.