On my laptop, I have both Mint-9 Fluxbox and LMDX with Fluxbox added.
I find Fluxbox easier to use and configure than Openbox. I have used Openbox for a couple years now.
Fluxbox has the ability of icons in the menu, and thanks to Kendall's script - Fluxbox has a self-updating menu.
. . . and full-transparency, of everything, without a 3rd-party App, (like xcomposing or cairo-composing)
Fluxbox, just seems more full-featured than Openbox.
Fluxbox, also, has better/more on-line resources and documentation available.
Fluxbox - easy, fast and light ... doesn't get any better than this.