To answer your question: Leaflet.draw is superior to mapbox-gl-draw. mapbox-gl-draw is very lightly maintained and is not as full featured as Leaflet.draw. mapbox-gl-draw sounds like it may also be no longer maintained by Mapbox in the future either - refer to the recent GitHub issue on the repos that hints at this.

There are mapbox-gl-draw plugins to make it comparable to Leaflet.draw but these are features IMO that mapbox-gl-draw probably should have had in the first place.

So, as someone who works with mapbox-gl-js a lot, that is something I see as a gap.