Went from the S6, to the S6 edge+ to the S7 (non-edge).
I saw a little bit more battery life with the S6 edge+ compared to the S6, and the S7 seems to be about the same battery life for me as the S6 edge+. I'm a light to medium user, so not an issue for me, and even the S6 had plenty of battery life for my general lifestyle (I do have a spare external powerpack for the days that I know I'll be away from a charger for a long time, but I don't think I've ever really needed to use it).
I like having the SD card, as it's easy to keep my files, photos, etc on a card which can be removed, replaced if needed. With the S6 variants, if you need to factory reset and miss backing up an important photo or file, you are SOL. With the S7, just remove the card and do the factory reset, and all of your files will be on the card. You should still make backups just in case, but the SD card just provides one extra layer of protection, IMHO.
There are slight differences in speed between the devices, but since I'm not a gamer, the differences are relatively negligible for me.
The camera is also better on the S7, but, as just a casual photographer (mostly photos of the kids), I don't know how big a difference it really makes.
The biggest issue I have with the S7 is the slight curve on the screen, making it difficult to find a good screen protector. The tempered glass protectors look like crap (They were a little better on the S6, I guess the curve wasn't as pronounced). I went back to a wet-install plastic protector, which isn't great, and still lifts on the edges because I am using a case. I've ordered another one that supposedly is designed for people that use a case, and will see if it works any better.
For anyone wondering why I went from the Edge+ to the smaller S7, it's because I got tired of pocket carrying a big phone. As much as I love the big screen on the Edge variant, it just doesn't carry well in my pockets. I decided to suffer the smaller screen for now (my poor old man eyes...).