In looking at many PHP editors in the last few days, Rapid PHP has the best balance of features. But, still it is lacking some things that I really liked from other editors. They are:
(1) A code beautifier.
(2) Ability to collapse a logic tree such as a function, if statement, loop, etc. UltraEdit has this feature and I think its great.
(3) Ability to flip back and forth between open files using keystrokes. And I don't mean like CTRL-Tab. I would like to be able to flip back and forth between the active document and the last one I viewed. Its very handy for comparing to another file. CTRL-Tab is nice, but with more than 2 documents open, it has to cycle through all the docs before returning.
(4) Ability to make the word wrap feature not wrap all the way to column 1. If a line is indented and word wrapped, it would be nice if the wrapped text stays indented.
That's about it. Hopefully these are in the works. I am still evaluating this program, but at this point, I expect to buy it.