Silent Hill gets my vote. It actually managed to translate the mood of the games over to the big screen.
The first RE movie was good but each sequel got progressively worse.
The first Mortal Kombat movie was good. Mortal Kombat Annihilation is one of the worst movies I've ever seen.
I didn't think Doom was terrible but it made no attempt to honor the source material.
I thought the first Tomb Raider movie was okay. Never saw the sequel though.