i don't know how the usb-c port sounds, but on the iphone, the lightning port has better sound quality than the 3.55mm jack. since usb-c was designed with help from the team that designed the lightning port, it probably also sounds better than the 3.55mm jack.
apple has, on numerous occasions, taken risky steps in attempts to revolutionize the tech industry. they popularized the touchscreen phone, and now, against all odds, they've popularized the removal of the 3.55mm headphone jack.
edit: i forgot that apple is adding the headphone jack back in their new phones. i don't have anything to say about that.