What convenient development environment would you recommend?

Question

IDE

Currently using nodepad++ for a specific project. It is very convenient: a lot of syntax, automatic placement of brackets, and similar usefulness. But there are also shortcomings in it, which I want to cover with a new environment.
The main drawback is inconvenient switching between project files, especially if these files are in the directories of this project. You have to keep the folder open in parallel with notepad.
It would be much more convenient if in the development environment, on the side, there was a list of directories and project files.
There is a very important feature. These files, from the point of view of the environment , are almost unrelated, unlike most VisualStudio projects. Think of it as a .php group-files organizing a common project, and which are located on a local disk in a folder. However, it is necessary to provide a convenient transition between these project files.

Answer 1

Sublime Text

Answer 2

phpstorm.
There is a free EAP version.

Answer 3

or Atom

Answer 4

Of those mentioned, neither Atom nor Sublime are IDEs, they are just text editors, although they contain a bunch of conveniences for programming. But if you like them, you might like Vim and ACME too.
The IDE mentioned here is actually phpStorm. And quite good, although demanding on computer resources.
Here is an overview.
www.sitepoint.com/best-php-ide-2014-survey-results
And here, judging by the opinions expressed and the survey at the link above, it is clear that for some reason PHP programmers prefer editors rather than IDEs.