My Primary smartphone, a terrific ultra reliable fast and highly useful Nexus 6 puts my wife's iPhone 6S Plus to shame.
It's a simple as that.
Well if you are happy and she's happy, then nothing to complain about.
But the "putting to shame" part I think you'd have plenty of 6S Plus owners challenging... me being one of them. I wouldn't use a Nexus 6 if you gave it to me for free, other than to just check it out. I used an Android phone as a primary device for 6 months earlier this year, and there was way to much friction with the rest of my, and my families, ecosystem. Unless I was willing to give all of that up at tremendous cost, anything Android will be put to shame with anything iOS, in my world. I'm not about having a feature race, I'm about maximizing productivity from my technology tools. They are tools after all.
The 6s Plus represents to me the best smartphone experience I've ever had, by quite a bit of margin.
Its good to have choice.