I use Homesite (by Macromedia -- former Allaire).
It's pretty good (features syntax highlight, etc.). Also the editor itself has many features that make me want to use it: the directory browse, project manager, in-program browser view, server mappings, coding options like outline current line, line #s, grouping code together so you don't have to scroll a lot in large programs.
But since I always like trying new program, i'll give codephp a try.
thanks for the info (although I think this question is more suited for the general forum)
-sridhar