I prefer a pressure bleeder to a vaccum bleeder for most of the time. I have found that pressure bleeding bleeds the system quicker than a vacuum bleeder does, if say you just did a line and need to pull a ton of fluid through, not to mention pressure bleeding seems to bleed more thoroughly, whereas you may have to rebleed with vacuum bleeder. Also, the noise from a vacuum bleeder can get old really fast(at least the vacula's).
My last complaint is that with a vaccuum bleeder, if the adapter isnt a perfect fit to the bleeder screw (which it never seems to be) it wont pull out a solid stream of fluid, making it hard to watch for any bubbles. Pressure bleeding is nice because you can actually watch the stream of fluid.
Jim