I don’t even know why Apple bothered with the iPhone 6, because it will go the way of the iPhone 5c: a niche product; a consolation prize; the budget choice for Apple loyalists; something you get begrudgingly and regret later.
One estimate is that the iPhone 5S sold 3x better than the 5c. I expect a similar breakdown between the iPhone 6 and the 6 Plus. OK, so the iPhone 6 is not dead on arrival, but it will be the ugly step-sister to Cinderella.
Except for personal preference over size and price, the iPhone 6 Plus is categorically the superior phone.