There is a lot of equipment out there, and some of it looks extremely appealing to beginners or non-divers, but proves to be unwieldy and unnecessarily complicated in practice. If you look at people who dive actively and persist in the sport over time, you'll find a definite trend toward simple equipment. It takes very little to make a BC -- you need an air bladder, a way to get air in and out of it, and some straps to attach it to the diver. The rental BCs which are used in classes are generally what's termed a "jacket" type, where the air bladder wraps around the diver, acting like a kind of life ring on the surface. These tend to be very large and heavy, and many people don't like the feeling of being compressed when the bladder is inflated.
You can also have a BC where the air bladder is all on your back. This makes the BC a little less bulky and makes it lighter. You do have to pay attention to fit and sometimes to your weighting, because all your lift is behind you (which is only an issue on the surface).
People often opt for pockets, but the pockets on many BCs are difficult to access while diving, and other methods of storing small items are sometimes preferable. Lots of people like what's called "integrated weights", where you don't have to wear a separate weight belt, but instead place weights into pockets that store in the BC. This has positives and negatives. It makes the BC bulkier. It makes it heavy to move around on land or on a boat deck, once you have installed the weights. The weights may or may not be located in the right place to make you balance nicely in a horizontal position (this is particularly an issue in cold water diving). It does do away with the need for a weight belt or harness. Many men have trouble wearing weight belts because they don't have much of a waist to keep them up.
At any rate, I would highly recommend that you not buy any equipment until you have taken your class. If there are shore diving sites near you, go visit some and talk to the divers (we LOVE to talk about our gear!). See if you find a common theme in what people have found to work for their environment. Don't let the dive shop talk you into the highest profit margin BC they carry, with all kinds of bizarre bells and whistles that may, in the long run, make your life harder rather than easier.
