Depends on several factors, what kind of HDTV, native resolution, and what ports you have available.
If the TV is 1080p, your decision making is a little easier as DVI and HDMI will be the same. If it's 720p though it's a little more complicated.
Most 720p LCD HDTVs are actually 1366x768. If that is the case, these are your options depending on connections available, from best to worst:
1) DVI
2) VGA
3) HDMI
4) Component
The reason why is that HDMI and component are limited in the resolutions they support, only 640x480, 1280x720, and 1920x1080. As you can see, the TV would have to scale the 1280x720 up to its native resolution, and that doesnt look that great.