All i can say is that my gf has a huawei and she can make 2 days of usage without charge easily. I have to plugin every 12h with my phone -_-
Thats a huge thing that actually is also a reason considering me to switch...
Yeah but how is that scientific at all? My wife uses Facebook all day, talks to handfuls of people, does Instagram, school stuff, all that on her iPhone. She'll barely last all day on her 8+. Meanwhile my iPhone 8+ will end the day at 93%.
Why? Because I barely use my phone. I've been able to get 5 days out of some of my iPhones ... because I'm a super light user.
A more accurate check would be to take the same person, one week use one phone, and the next week use the other phone. This gives the phones a few days to settle in and have the SAME usage from the same person over a set of time.
My device usage includes: (HTC My Touch, Droid 1, HTC Thunderbolt, iPhone 4s, iPhone 5, Note 3, iPhone 6+, Nexus 6 (short time), iPhone 6s+, Google Pixel (short time), and now an iPhone 8+. I've used iPad 3, iPad 4, iPad Mini 2 and 4, Samsung Galaxy Tab S3, etc...
My experience? iPhone has much better standby time. Android used to have HORRID standby time (why, as this thread mentioned earlier, some people used Greenify or rooted (I did) - now that's all handled by the OS) -- still, My Samsung Galaxy Tab will sometimes last 3-5 days and sometimes, in one day it'll be dead without me touching it. My iPads could last weeks with my usage. The Nexus 6 was horrid on battery compared to the 6+ and the Pixel... well I can't really say anything about that cuz I didn't use it for more than a day.
Android is getting better. But to compare someone elses usage to your own is really unscientific. Android users at the airport hate me when I say I can get 5 days of usage out of my iPhone because they love to spout how terrible Apple battery life is... Meanwhile I'm handing them my Anker battery brick....
But my usage is super light and I don't use social apps. That seems to be my wife's biggest battery usage.