The vest style BC inflates chambers all-around the body (front and back). The back inflated BC is as the name suggests, only inflates a bladder around the tank. My preference is the back inflated for two primary reasons. One reason is you tend to level off better with less tendency to roll from side to side. The other main reason is I find they release air easier during ascents/descents and working your boyancy control. Another reason that may not apply to the recreational diver is some of the back inflateables have the ability to switch bladders from the standard 45 lb lift upto 85 lbs of lift. These are the technical reasons, the other consideration is comfort. I remember during my training renting the vest type and at the surface I'd have it filled completely with air squezing my lungs so then you losen for comfort. When you descend and release the air (which sometimes has to be squezed out because it gets trapped in the vest) the vest becomes loose. With my back inflated it has a harness that fits the same at the top as it does at the bottom and the bladder expands outward from the back. The BC is a critical part of your scuba enjoyment choose wisely. Hope this helps. Have big fun diving!
[This message has been edited by Zoid (edited 09-07-2001).]