Glad you like your new iP6+. It's a great phone. I've been considering S6 for a while since I heard lots of good things about it (I've never used an android so I have this longing to try one out) but I highly doubt I would replace it for my iP6+.
Thanks. I think you're making the right decision as well since your 6+ offers better battery life, easier to use camera software, more apps, presents better information in the form of "Widgets," a bigger display, faster updates, iMessaging, Apple's Apps and Services, you don't need to rebuy apps on the Play Store, iCloud is convenient, etc.
What the S6 offered was better features, a nice build quality (fragile though), a kick ass camera with the double tap launching feature, a slimmed down touchwiz (still problematic though), a vivid display (albeit smaller and unnecessarily powerful), amazing SoC architecture (14nm Exynos), tons of RAM, and curved sides on the Edge.
Is it worth that stuff if you have apps force closing (Amazon app that you cannot delete and only disable), wifi calling doesn't work with VOLTE unless you want less battery by a country mile, aggressive RAM management bugs, screen flickering bugs, heating from time to time, lack of battery life, Touchwiz lagging from time to time, getting updates really late? To me it wasn't so, I switched to the 6+. I suggest you do not look at the S6 at all since the Note 5 will be the best Samsung has to offer. I think I am going to stick with Apple for future generations due to my skepticism towards Samsung and carriers.