title: Making sense out of Emacs completion mode choices
body: <p>There appears to be many alternative Emacs auto completion mechanisms.  Without an exhaustive search, the following come to mind: ido, auto-complete, icicles, in buffer completion, minibuffer completion and standard out of the box completion.  And then there is code completion.  Lots of it. And much of it language dependent.  It would be very useful to have an Emacs guru, or three, summarize the benefits of the major players in both code and non-code auto-completion.  And this being Stack Overflow, it goes without saying that it would be good to identify the auto completion modes that work best for Emacs's IDE-like mechanisms.</p>
  
  <p><strong>Update</strong>: I just discovered <a href="http://www.emacswiki.org/emacs/CategoryCompletion" rel="noreferrer">the Emacs Wiki completion page</a> which amplifies my basic question: of all these choices, what's good, what's less good and if you could only play with 2-3 which would you recommend?</p>