To be precise, there's only one backgrounder app, and that's backgrounder. The others are app/task switchers.
To answer your question, after trying all of them, I've actually decided to go with just backgrounder. I set it to activate on a double tap of the home button (otherwise it's too confusing with also having an iPhone on iOS 4 / native "multitasking"). I can tell which apps are backgrounded by the badge.