Let's Compare and Contrast
When comparing bone structures, Pterosaurs and Birds have lighter wings than bats because they only have one "finger" instead of a bunch of spread out fingers. Bat wings give more control over the shape of your wing which is good for maneuverability, but bad for weight to lift ratios.
Pterosaurs have a slightly better wing shape than most birds for being big because thiertheir wings have more of a distal tapper. By having more area closer to the body which tappers out to the wing tips, there is less leverage working against holding out thiertheir long wings straight. In contrast most bird wings are designed to more evenly distribute lift.
Birds also have the advantage of feathers which extend the available surface area of a wing while adding negligible mass making bird like wings in many ways ideal for larger animals. (Pterosaurs had feathered wings too, but it is uncertain if they had flight feathers.)
In a related question: Could my Wyverns exist? I went into a bunch of details about optimizing lift against square cube rule disadvantages, but what it really comes down to is that the bigger you are the more you need to pancake or hallow out your mass to be able to fly; so, while wings shape is important, it is not necessarily as important as answering how you can turn the most mass into wing surface. To this end bat wings may be the best because they unify thiertheir arms, legs, and tail into one big continuous flight surface.
So your Best wing shape may actually be to take the best of three worlds. Use the distal taper of the Pterosaurs, the feathers of birds, and the continuous flight surface of a a bat which together will give you something similar to this: