Both "Night" and "Dawn" loomed large over my childhood, in terms of horror movies, and movies in general. I remember one Halloween season my friend's Dad brought home the VHS of "Night", and it had us riveted for the whole afternoon and set forth a life long interest in horror/zombie movies.
I think "Day" is a disaster and his later work became very hit or miss, and that's being generous, I couldn't believe how bad that last one was, it was unwatchable. "Survival Of The Dead", I think. I did like the one in 2008, and his vampire movie "Martin" is a creepy little underrated horror movie.