The correct answer is "It doesn't matter so long as the method used meets your desired resolution/refresh rate".
HDMI and Displayport both do fundamentally the same thing: Transmit Video and Audio between two devices. Typically, Displayport has tended to support higher bandwidth then HDMI; for example: HDMI 2.0 can't handle 4k120 with HDR enabled, where Displayport 1.4 can. But as both are digital, to the end user, they offer the same image output so long as the resolution/refresh you choose fits within their transmission limits.