None. The guys recommend D-Spark from N2BM.com as it's a non-stim.
All of the most popular have massive doses of caffeine in them. Some have your recommended daily dose in a single serving (400mg). Even as a coffee lover having the same as 4 strong cups of coffee in one hit is too much.
One of the other mods, Stevesmi, rightly points out that for bodybuilders stims actually cause blood vessels to do the opposite of what you want - you want them to dilate (open up). I'm a strength athlete so it's good for me.