Hard to beat the standby time of the iPhones. I have an iPhone 7 and a Pixel and love them both but the iPhone, in all honesty, just slays the Pixel when in idle. Screen on Time is also advantage iPhone but not by as much.
The Pixel is probably the best Android phone as far as battery life is concerned but there are so many rogue and runaway (and legit) processes running on Android phones compared to locked down iPhones that they will never deliver the battery performance Apple can.
That said, you are trading battery life for considerably more flexibility and many more features so for many, that's a trade worth making.