Well as I can see your monitor is indeed 1080p ! Well vga is simply analogue while hdmi is digital. I would suggest to go with hdmi simply because I always like to keep up with technology and hdmi is for sure one of the latest
Theoretically though, Digital video (DVI/HDMI) is better than analog (VGA), but in real life the human eye sees no difference.
For more info read through this article:http://www.ehow.com/facts_5786244_hdmi-vs_-vga.html
Hope this helps!