Not just for PHP, HTML and JavaScript, but especially good is SQL inspection and auto-completion of tables and fields. You can see at a glance, that your DB structure is in sync with your code.

Quickly rename classes, methods, and variables used across multiple files in the project.

This allows execution of needed commands without switching to other windows. It also keeps track of what's happening right in the IDE, which is especially good with Vagrant, because you can connect to a VM in a single click.

Allows users to manage their repositories directly from the IDE with a GUI which lets you do all Git commands.

The database tab, while not perfect, provides all the tools you need for daily usage. You always have your DB overview on the side (you can hide it when not needed).

PhpStorm has two types of autocompletion: structural completion and word expansion.

Structural autocompletion makes predictions based on its understanding of PHP, while the latter tries to predict the word currently being typed based on previously typed words. Word expansion also works in comments and docstrings and it's similar to vim's omnicompletion.

Both types of autocompletion work extremely well, have little to no problems and are quite fast even when loading suggestions on the go.