My all-time favorite is White Zombie (1932) starring Bela Lugosi. But as far as modern zombie movies go, my favorite is still the original Night of the Living Dead (1968) despite the bad acting; I like Tom Savini's 1990 remake as well. Second on my list would be Zombie (a.k.a. Zombi 2; 1979). And, although it's sacrilegious to most zombie movie fans, I prefer the 2004 remake of Dawn of the Dead over any of Romero's other movies (except, of course, for the aforementioned NotLD). Also, despite the truly awful acting and horribly dated wardrobe, I have a real soft spot for Children Shouldn't Play With Dead Things (1973) because it was the first zombie movie I ever saw and, because I was only 12 years old when it was released, it scared the hell out of me (the only time I can recall any movie having that effect on me).
For zomedies, Shaun of the Dead wins top honors in my book, closely followed by Zombieland, which is closely followed by Return of the Living Dead.