Parts 1, 3, 4, and 7.
Part 4 is my absolute favorite after 1, as I greatly prefer Alice over Nancy.
I love the effects (cockroach death!), the soundtrack, and the film's visual style overall. The only drawback is Tuesday Knight, as Patricia Arquette is the only Kristen.
Here's what I just found on youtube:
A Nightmare on Elm Street 4 special in three parts:
1 2 3