I use both the SD and have Google Photos automatically backing them up. There are lots of benefits, namely that as long as you choose High Resolution backup, there is unlimited storage for your pictures to back up. That is huge (as opposed to other fruity devices that only allow up to 5GB backup space).
Having the assurance that every picture I take is automatically backing up is priceless. Too many times I have had an SD card or a phone crash with non-recoverable pictures. In the past, it wasn't as big a deal as the cameras weren't all that good so I didn't use it as much. But with the camera on the S7, I find myself forgetting my DSLR camera and using the S7 more and more often.
Another thing, it sure makes sharing photos/photo albums easier - just provide the sharing link and that album can be accessed by the person you give the link to. And it makes it easier to get pictures to my computer. I take the photo, then when I get home I just look at Google Photos via my browser on my computer and the picture is there to either share,download, edit, whatever.