I watched Batman (1989) on Saturday. It is still, by far, the best film involving Batman.
I did enjoy The Dark Knight, but all the hype was clouding my judgement. It's still a good film, but not as good as the Keaton/Nicholson/Burton version.
This is how I'd currently rank the films:
2. The Dark Knight
3. Batman Begins
4. Batman Returns
5. Batman Forever
6. Batman and Robin
One other thing....
Jack Nicholson was a better Joker than Heath Ledger.
I know Heath won an Oscar, but he wasn't as good as Jack (at least in my mind). Put it this way: Heath had the look. Jack had the character.