The iPhone will serve you better when it comes to using Continuity and Handoff. All your Apple devices can communicate with each other over cloud so you get a 'seamless' kind of experience. Thats one reason to have an iPhone instead of any other.
If its technical superiority you're concerned about, the 6s and 6s+ pretty much cream the latest Samsungs in cpu/gpu/battery performance, if you look up Anandtech's reviews (the most detailed and elaborate I have found).
These 2 points address your concerns about the latest iPhone. There are things such as display and camera quality where Samsungs might be preferred, but that's individual choice - as is your choice of operating system and UI.