The draw distance, ground detail, and traffic is alone worth it for me. That, and especially, less repeating cars.
I'll often use GTA V as a sort of screen saver. Park Trevor somewhere with some sort of theme, like wearing a security vest and with the Sheriff suburban by the Paleto sherrif wall mural with the flags and radio tower in the background, or wearing a brown suit and full gerrybeard a la the Trevor Philips Industries drug kingpin with a white Rolls Royce out in the Grand Senora desert in the midst the oil derricks, or with a Gwagen in work clothes out at the ports, just watching the sun through the Paleto pines or glistening sand dunes and the creek of the oil derricks or watching the semis drive through the port authority.
I'll leave that on all day on a TV while I'm working in my office, amid the clutter of Bloomberg and market screens on my various other screens and tablets. It's actually surprisingly how good a screen saver or 'background visual/noise' the game is.