Either HDMI or VGA depending on the situation. HDMI is technically the superior interface, since the signal doesn't have to be converted to analog and then back to digital. But if your TV's native resolution isn't supported by HDMI, the picture will look blurry since it would have to be scaled. If that's the case, VGA is probably the better choice since it supports more resolutions and, as long as your graphics card supports it, should work at your TV's native resolution. Even if HDMI can handle your TV's native resolution, there probably won't be a noticeable quality difference between HDMI and VGA though, since analog-digital converters are pretty good these days.