I'd say 2 is the scariest, just because of the idea of Freddy taking over someone's body in their dreams and making them kill people in real life. Now that's fucked up. At least in the first one, Nancy had her friends going through the same things. Jesse was all alone. Although so was Nancy at the end of part 1, and 1 had a better ending. The lead up was great though with Jesse finding the glove and Freddy and telling him to try it on, finding Nancy's diary and slowly learning what happened, and things like seeing Freddy's reflection in the mirror.
It also had this exchange.
Stupid kid: Calm down man, we want to help you
Freddy: Help yourself, fucker!
(stabs him)
With scenes like that, how could it be a bad movie?
1. A Nightmare on Elm Street
2. A Nightmare on Elm Street 2: Freddy's Revenge
3. A Nightmare on Elm Street 3: The Dream Warriors
4. Freddy vs Jason
5. A Nightmare on Elm Street 4: The Dream Master
5. Freddy's Dead: The Final Nightmare
6. Wes Cravens' New Nightmare
7. A Nightmare on Elm Street 5: The Dream Child