I decided to give the Plus lifestyle a go so I upgrade from a 6S to a 7+
Main reason was battery life, with the iPhone 6s I couldn't get through a day without either totally running flat or having to turn on low power mode. I tried an Apple battery case, however found it was too bulky.
All I can say is wow, for battery life alone, not to mention the Camera (I don't use my Sony 5X anymore), it is well worth the minor size difference (especially when you compare the 6S with Battery case to the 7+).
If it was an iPhone 6s > 7 decision, I'd wait for the iPhone 8 if I could.