Well being that I saw Night of The Living Dead in a drive in at age 10 in 1973, I'll go with that as my main fave.
Others include:
Let Sleeping Corpses Lie aka
Living Dead At The Manchester Morgue
Tombs Of The Blind Dead
Zombie
House By The Cemetery
The Beyond (also known as 7 Doors Of Death in it's cut form.)
Invisible Invaders ( a true 50's atomic age classic.)
and right now I need to think of more but that's a start.