There might be a good question in there after all. You evaluated some of the suggestions and updated the question accordingly.
The trick is: You should have done all that before asking.
All the popular PHP IDEs are easily found with a simple web search. The commercial ones have freely available scaled down and / or trial versions. The effort required to evaluate them is not something you cared to skip, either way, as I'm guessing you wouldn't blindly follow what some random dude wrote on the internet.
Let's say for example that you evaluated Zend Studio, Eclipse PDT, PHPStorm, Aptana, Emacs and NetBeans and you settled on PHPStorm, whose commercial license currently costs $199. It's understandable that you might want to ask before paying that, so such a question would probably be fine, because:
- You have done a fair amount of effort,
- By presenting the reasons why each solution doesn't fit, you've given us a very good idea of the specific parameters of the question,
- Your question is actually practical and answerable, based on an actual problem that you face.
- You are not asking for a generic list of bests, but for the best for you, having clearly outlined what that means.
- A good answer to this question requires expertise, whereas the answers you got may or may not be the result of a simple web search for PHP IDE...
Simple, isn't it? I know that would lead to a different question, but the point is that it would be a question that would help you solve the same problem, choosing a PHP IDE.
As for your specific points:
the question long lived before being removed
System failure. It might have survived long, but that doesn't mean by default that it was a good one, it might also mean that the community didn't do a very good work cleaning up...
it was pretty popular
Although I agree with Charles that it really wasn't, even if it was, so what? Popularity alone not a good question makes. I've just had a popular answer deleted, for good reason. It was a joke answer, people up voted it just because it was funny (and on a Friday), should I nag the mod that deleted it?
it was actually a "constructive" question, providing info about most of popular PHP IDEs, and offering answers / discussions about them.
Not constructive is Stack Exchange lingo, questions that lead to discussions are not constructive, plain and simple. Your question, albeit bad in Stack Exchange terms, is possibly constructive and interesting in real life.