I have a C2 and an Apple TV 4K. Apple TV is better, easier to use and faster than the software in the TV. However, and this only applies in UK, the BBC iPlayer app is much better on the C2 (has UHD/4K support and the standard UI) and integration of Freeview Play (SD/HD TV through aerial - DVB-T2) with the C2 apps for the main channels is pretty slick (e.g., if watching a BBC broadcast a prompt tells you if the programme is available in UHD on iPlayer and loads the app and starts the programme with one button press).
I have a C2 and an Apple TV 4K. Apple TV is better, easier to use and faster than the software in the TV. However, and this only applies in UK, the BBC iPlayer app is much better on the C2 (has UHD/4K support and the standard UI) and integration of Freeview Play (SD/HD TV through aerial - DVB-T2) with the C2 apps for the main channels is pretty slick (e.g., if watching a BBC broadcast a prompt tells you if the programme is available in UHD on iPlayer and loads the app and starts the programme with one button press).