Haloween was great, and part 2 was a good continuation of the story. Part three was original and creative, but didn't catch on. Would have been great if it were titled anything other than part of the Halloween series.
Evil Dead is great b/c of the comedy. The first two were only comedic at points, but by the time part three (Army of Darkness) came out, it was pure comedy.
Part 2's story was ok, I guess, but the movie itself was just bad. I think the only reason it was made was to make Laurie out to be Michael's sister. The original premise was Michael was stalking the two kids who showed up on his doorstep (isn't that why he stalked both Tommy and Laurie at school?) Then he stalked the other girl because she yelled something at him as he drove by.
But once she was made out to be his sister, it opened up the door for more sequels. I watched part 3 when I was a kid. I honestly don't remember much about it. 4 and 5 were pretty good continuations of part 2's story. Part 6 was awful all around. I bet Paul Rudd wishes he could take that off his resume. H20 just completely ignored 4, 5 and 6. Resurrection seemed like it was a random slasher flick with Michael Myers written in as an afterthought.
Rob Zombie's original remake added some depth and had some good parts. I just think he went a little overboard on the Myers being complete white trash trying to explain Michael. His Halloween 2 was so bad it was painful to watch.
But I still put the original Halloween up there as one of the best horror movies of all time. The camera work was brilliant - you actually get the chills watching Michael stalk people in the background. There's something about seeing people live their normal lives, then seeing a psychopath moving around outside their window that's spooky.