VGA output is an analog signal, while DVI and HDMI output is a digital signal. DVI and HDMI can output full HD 1920 * 1080 digital signal, except that HDMI video and audio signals are in a group of lines from a plug in output, while DVI only output video signals, audio signals have to use another audio cable from the sound card which is connected to the audio input port TV. Because VGA is an analog signal, no better than digital signal. If you take the high-definition TV, general it can only maximum output 1366 * 768; VGA Optical mulitplexer has good compatibility, most monitors are the use DB15 interface compatible with VGA signal, so use more common.
DVI is a high definition digital video transmission formats adn it could meet the needs of high-definition display currently. HDMI compatible high-definition display, packed digital audio transmission, so it could better meet the user of the video, audio for high demand.