After it being recommended to me, I decided to give Brain Dead a try. Didn't find it funny in the slightest. Felt like it relied mostly on being shocking and not much else.
The Evil Dead trilogy on the other hand (especially Evil Dead 2), are still some of my favorite movies.
As for Land of the Dead and Diary of the Dead, yeah, I felt Diary was extremely weak, but watched it alongside a ton of other zombie flicks, and actually felt it was on par. Not exactly a sub-genre that aims for excellence. However, I liked Land of the Dead, and felt it ranked very high among the best modern zombie films.