One of the features I am most excited about with Sierra and iOS 10 is Universal Clipboard. When you copy something on your Mac it is available to paste on your iOS device.
I like to use my devices together and this really moves that forward. Especially copying complex data on my Mac to paste on iOS. Since iOS selection is not always the greatest and takes a long time to accomplish in certain situations, this helps out.
I look forward to more features that combine the usefulness of all devices when used with each other.