If you live in a particularly hot and sunny area, morning sun and afternoon shade is best. Mulch and morning mistings help in extremely hot climates. Everyone has their own particular microclimate so it is best to provide as much shade as possible when you are in extreme hot areas.
It is important to realize that the roots of Japanese maples are shallow growing and will over heat in hot climates. This will show up as leaf scorch just like the sun burning the leaves. For that reason, it is a good idea to lay mulch 4-6' around the base of your tree.
All these trees can pretty much take the full sun to 85° without much problem. If it exceeds that - then morning sun and afternoon shade is important for successful growing of maples.