The light LEI actually handles extremely well in marginal winds.
The superlight strutless one are exceptional.
Where a normal race foil kite can not match, because it drops easier and folds if wind is gusty, so a lot more tricky.
In steady winds, the UL foil kites are awesome, but the UL strutless LEI can really hang without the same issues nor risk, in marginal winds.
BUT, they can not ride in the same low wind as the foil kites, as Pedro also writes, not sufficient (peak) power eventhough they hang really well.
You only asked which type hangs in the air the best, and they are pretty close the UL ones both LEI and foil kites IMO.
But LEI a notch better than most foil kites if wind shifts or changes because of their rigid structure, and the foilkites definitely the ones that can give you the best options to ride in the lowest wind, but at a higher practical cost if it goes wrong of course
Impossible to say anything in general as particularly foil kites are so different, but still....