Yes and no.
Being a giant predatorial pterosaur that was apparently able to travel long distances, quetzalcoatlus, as well as other azdarchids, is considered a very successful pterosaur species, with their "reign" over the skies ending with the KT extinction event. With this information, we can clearly see that Quetzalcoatlus had the best wings for a creature its size...which predominantly relied on soaring and very powerful but spread apart flaps of the wings. Their wings were capable of sustaining them during flight, allowed for long distance travel and permitted their lifestyle.
So did the Quetzalcoatlus have the best wing design for a large creature with a lifestyle like quetzalcoatlus'? Yes. Was it the best wing configuration among all possible kinds and superior to any other wing in every way? No. Quetzalcoatlus showed is that pterosaur wings allowed for large flying creatures to exist, but I doubt that quetzalcoatlus would ever be able to catch a flying bat (wild speculation but, yes), because bat wings, with their large amount of articulation, allows their owners to do incredible acrobatic and evasive moves, as well as achieve decently high speeds in certain species, with the Brazilian free-tailed bat being the fastest flying vertebrate regarding powered flight, clocking at 160 km/h.
So that means bat wings are superior? No. Bat wings may allow for decent speed and great maneuverability, as well as high dodging capabilities and some level of hovering in certain nectar-feeding species. But in many cases you'll hear a bat flying by the sound of its flapping motion, something that'll hardly happen with an owl. Owls evolved special feathers that, combined with their slow flapping flying style, makes their flight almost soundless, so by the time you detect it, it'll be to late. Falcons on the other hand went for the "opposite" strategy, you'll hear them coming, but with their body an wings adapted to achieve high speeds (peregrine falcon still holds the record for fastest flying animal with its 320 km/h dives), it'll usually be upon you before you have time to do anything.
So summing up: did quetzalcoatlus have the best wing for a quetzalcoatlus? Yes. Was it the best wing ever? No, it wasn't.
As far as it's understood, what allowed pretosaurs to reach the sizes azdarchids did wasn't just the wings, it was about the pterosaurs themselves, their extreme adaptations which resulted in animals the size of a giraffe that weighted less than a black bear and were assumed to take to the skies like a vampire bat.