Well, I've got both a Galaxy S8+ and an iPhone 8 Plus and I know my S8+ (and indeed any other decent Android device) is capable of doing more than the iPhone, but I just don't care. I simply prefer using iOS and since my only other iOS device was a knackered iPhone 6 Plus and I don't fancy the X, the 8 Plus was the logical choice for me. Well, aside from a 7 Plus, but it was only £30 difference between a 7 Plus and 8 Plus anyway so seemed a no-brainer. I suppose I could've saved more cash by buying a used 6S Plus or 7 but I wasn't too fussed.
It's weird, I know Android can do more, but it just doesn't matter one jot to me. Reminds me though, need to get my S8+ up for sale since it's just sitting in its box now and I forgot about it

No surprise about the iPhone 8 sales potentially not being that great though but it is all speculation at this point since they're unlikely to talk figures. It's obvious that most people will be waiting for the X though, so they've sort of shot themselves in the foot there.