I am struggling to make a final decision

I have the smaller S8 and battery life is acceptable, BUT not as good as my iPhone 7 Plus.
I find it not bad at all really. I just top off here and there and I always have plenty. It doesn't drop suddenly where I've seen on other Android phones but it's a slow decline plus not dealing with a huge phone is nice! I also have a battery case I got from Amazon that I use for camping and other trips that will last a long day without touching a charger. The phone is huge with that case on. Can't imagine what a plus would look like with the similar case on. I may go with the big one next time but for now this works great
 
I find it not bad at all really. I just top off here and there and I always have plenty. It doesn't drop suddenly where I've seen on other Android phones but it's a slow decline plus not dealing with a huge phone is nice! I also have a battery case I got from Amazon that I use for camping and other trips that will last a long day without touching a charger. The phone is huge with that case on. Can't imagine what a plus would look like with the similar case on. I may go with the big one next time but for now this works great

Correct it's not nearly as bad as earlier galaxy phones and other Androids, it's just not quite in the iPhone Plus league, which I suspect the S8+ may be because of the larger battery. I think you would be fine with either phone, the main deciding point being size preference. :)
 
I've been an Android owner from day one but the past few years have switched back and forth between iOS and Android. I was pleasantly surprised at the battery life of the S8+. I knew it wasn't going to be as good as my old iPhone 7+ but it is much better than the Note 5 I owned a couple of years ago.
 
I've said this before but I might as well post it again. I'm not thrilled with the length of the 8+ but I want the battery and screen real estate.

I think the dimensions of the Note 5 are optimum. (But that's about the only thing I like in this model. However, that's a different story.)

Anyway, when I went to a well padded, luxuriant leather folio/wallet case I found that the hard, unyielding edges of the S8 were no longer uncomfortable and a problem. The device felt smaller and more natural in my hand. That's my story and I'm sticking to it.