Use either VGA or HDMI (if you have it). S-Video will be much lower quality, and you will be able to see it in the picture.
I used VGA for a couple years with zero problems. I recently changed to HDMI on my PC video card (because my new TV didn't have a VGA input) and I have had nothing but problems. As far as I can tell, the problems are caused by the HDMI output on the video card. If I had a VGA input on my current TV, I would definitely use it over HDMI. Of course, there may be some technical details of which I'm unaware that would make HDMI a better choice than VGA. However, I do believe that either one will do 1080p, and that's pretty much as good as it gets (I'm using "only" 720p, FWIW).