I will try and keep it simple. First decide if you want integrated weights (that is weights that are configured so that they can be carried as a part of the BC rather than wearing a weight belt), or if you prefer to wear a weight belt instead. Much of that is personal preference. Below is a HIGH LEVEL overview. There are so many BC's on the market now with so many different configurations and features...the clean delination between groups is becoming a little fuzzy sometimes.
Jacket - The air bladder "wraps" around your sides. This is, generally speaking, the most popular style used by sport divers. (You see a lot about BP/W here on the board, but we are all fanatics...so allow for that).
Advantages are you get pockets to put stuff in, when on the surface it generally acts (not designed to be, but acts) like a life jacket. Some models have integrated weight ability, some do not.
Disadvantages - Some do complain about feeling "squeezed" when fully inflated. Might be that a bit larger size would have remedied that issue, but who knows. I know the first jacket style I owned I could push enough air in it to feel that...but it was totally absurd because I would float like a cork. Because you have the bladders wrapping around you, it will feel a bit "bulky". Most severe disadvantage is that should you elect to someday go into a form of diving using double tanks, most (if not all) BC's styled like this will not allow fitting doubles onto them. As far as the "air rolling from one side to another" I personally have never seen that happen unless the user wore one way too big for them, or it was not of a very high quality. For 500 you can get a pretty decent one where that would not be an issue if it is sized correctly.
Rear Inflation. The air bladder is to the rear, and does not wrap around you. Again a fairly popular style.
Advantages - some have pockets you can stuff things in, better models (probably out of your price range, but not much) will accept double tanks with the addition of some hardware, however usually you may have to upgrade the bladders to a higher lift capacity depending on the model you bought to begin with. Because the air bladder is behind you, there is a sense of a bit more freedom of movement. Many of these have metal rings on the harness or belt that you can clip accessories to. Again, some come with integrated weights, and some do not. Zeagle BC's (I am not that familiar with other brands as I have one of these) are modular to a degree where you can replace components such as the wings if they wear out.
Disadvantages - Generally you will have to "trim your weight" with this style. What that means is that depending on what kind of tank you use, the bouyancy of that tank can vary. Many of these style BC's have weight pockets as a part of the tank bands so that some of the diver's weight can be placed in them to assist this. Again you will hear comments around "it wants to float me on my face" and it will...if you inflate the bladders to capacity and have no tank trim weight. With a little practice you can actually roll against the bladders and lay on your back much like an air mattress.
BP/W (Backplate and Wing). A stainless steel or aluminum metal plate with a web harness attached to it. Also attached is a "wing" (airbladder). The harness in it's base form does not have pockets, but they can be purchased as add-ons, as can pockets specifically designed for weights to be stored with a quick release mechanism in case of an emergency. Backplate setups can be extremely varied if you decide you want to go this route.
Advantages - Can easily accommodate both single or double tanks with some very minor modifications. Probably more a feeling of freedom of movement than the previous types. Is extremely flexible in terms of fit to the user...since you are in essence using a web harness, it can be sized exactly to you versus having to live with "small, medium, large", etc. Is also flexible in terms of attachments...you can go bare-bones" or put in accessory pockets if you want those. Will usually have "d-rings" similar to the back inflation model for clipping extra gear to. A fairly large variety of wings can be fit, including ones with different lift capacities and even ones that are double redundant with dual inflation hoses and bladders. One of the largest advantages in my mind is that the whole thing is modular. If a piece wears out, such as the wing, or the harness, you can buy that one piece and simply replace it rather than having to reinvest in an entire new unit. Because of the way these units are constructed, with a metal backplate, you will probably be able to reduce the amount of weight on your belt by several pounds.
Disadvantages - Not very many however the wing portion needs to be purchased a bit more specifically to your diving. A larger wing designed for doubles may not do well with a single tank, and certainly there are wings designed more for singles that will not accomodate doubles (but then getting an additional wing is cheaper than a new unit, and can be fitted in a short time period). Many owners of these type BC's have more than one wing, or several setups, depending on if they are going double tanked or single. Depending on brand, capacity, etc, you might be able to get in under 500.
In the end...do an appraisal of what you think your diving future is. If you right now think you would want to dive for a while and after time go into techinical diving or another form requiring double tanks...you might consider the BP/W setup (you can get a wing designed for a single tank setup and progress to an additional wing for doubles if you go that route). If you are going to probably be doing single tank setups and just having fun for the next 3-5 years go with a jacket or rear inflation type. You can always go BP/W later and keep the jacket for those trips where you are going to just do single tank diving.
I agree with almity...a Zeagle is a good way to go to start (they are high quality, some of the models will take doubles, and they are rear inflation). Having said that, I do have a Zeagle, but I also have a BP/W unit as well. But I would also caution that this really is a personal choice...and I would encourage to read and follow Damselfish's advice as well. In the end...you are the one that is going to own and wear it!!!
), alot of divers buy their 1st set then later on find it doesnt suit their diving (ie, go to twins/tec, they dont like the clutter a traditional jacket has ect) and ive found this gear adaptable
