I think you're thinking about this the right way -- i.e., you seem to have a good handle on the pros and cons of each possible recommendation writer.
In general, more recent is always better, not only because the stories are in fact newer, but also because usually your older stories involved jobs/projects/situations in which you had less responsibility than you do now. If you were a junior assistant to the associate consultant way back when, then the stories about your time in those situations will be less interesting than if they're about a time when you led a team, etc. But, if your older stories are still ones in which you had some responsibility, demonstrated your leadership and teamwork skills, etc. then one of the older stories could still work for you.
Also, don't forget to look outside your job... If you have a great recommendation opportunity there, I'd seriously consider it as well.
Of the four you listed, knowing very little about them (of course), I'd rank them like this:
BTW, we've written extensively about MBA letters of recommendation on our blog:http://blog.veritasprep.com/2010/05/let ... r-you.html