If you are connecting to a VGA-only display, ultimately, you will be limited by the VGA, which is an analog (not digital) signal. Either HDMI, or USB-C/thunderbolt will give you a decent enough signal, limited to the quality available on the display. One limitation that you will easily notice, is when connecting to a display that is some distance away, say more than 50 or 60 feet, like an overhead projector. Long VGA signals will be affected, quickly losing brightness and definition. The same length of digital (HDMI or DVI/other digital video connection) is not as quickly affected by cable length, and digital/analog signals are not affected by a local video connection, meaning less than 6 to 10 feet from computer to display.