HDMI worked, but DisplayPort unlocked everything.
As long as you're gaming within specific resolutions and refresh rates, HDMI 2.1 is just as capable as DisplayPort.
I have a Dell U2720Q monitor that accepts HDMI 2.0, DisplayPort 1.4 and USB-C. I use USB-C because the monitor acts as a hub for a range of peripherals (keyboard, mouse, webcam, speakers, etc.etc) and ...