I would suggest vim for any type of serious code development and/or debugging.  There is a file called "tags" in your moodle/ directory that contains a list of sorted functions, variables, etc. that can be accessed directly if you're using vim.  For instance, let's say your browsing code in your editor and come across a function, moodle_foo(), and you want to see its implementation.  Move the cursor over the function and hit CTRL-], and you will jump directly to the function definition.  You can then use CTRL-T to go back to where you were.  This is only a very small fraction of the things you can do with vim...highly recommended!  I've been using it (or a variant) for many years, and would never consider using another text editor for coding.