If you are thinking which new iPhones you wanna buy (either iPhone 6 or the 6 plus), here's a good video that shows how three iPhones (5S, 6 and 6 Plus) can fit into your jacket or pants.
In the end, I think it depends on the user. As for me, since I'm only 5 feet 4 inch tall, my trousers are not as large as tall guys. And most of the time, I place my iPhone 5S onto the belt case. Rarely I placed my 5S into the pants pocket. And imagine wearing a 6 plus with a belt case - don't you think it's slightly too large..?