There's alot of choice. I believe the Macromedia offering has been well received.
I use editpad lite for basic changes and I use PHP Edit for anything major.
PHP Edit's free and IDE which means it's got syntax suggestions and everything. It does crash but so infrequently as not to matter. Occassionally it asks me something in french where the "internationalisation" hasn't reached that far and I click "oui" or "non" depending on instinct. Worth the effort to download and trial.