A scuba buoyancy compensator comes in trhee basic types
Each type has its own pros and cons making them more or less useful for different types of diving and different diving styles.
Vest or Jacket - The most common by far is the vest style bcd.
Worn like a vest it can come with a ton of features or as stripped down as you want.
Depending of the features, quality and brand a vest style BCD can be either cheap or expensive.
One downside are the inflatable bladders that wrap around the body. When you inflate your bcd it can feel like it's squeezing you.
Wearing the right size will make it more comfortable when inflating your vest style bcd.
Wings - These are becoming more and more popular.
in the past They were used mainly by Tech Divers because they allowed for the greater customization of gear that is necessary for technical diving.
Now though there are several models of wing and hybrid wing/vest bcds that are marketed to the recreational diver.
A novice diver may feel uncomfortable in this type of scuba bcd because the back inflated wings can push you forward in the water when you are floating on the surface. A little practice will help you compensate for this.
Horse Collar - This is an old style buoyancy compensator that you will rarely see in use today. They look and fit like the old over the head life jackets.
One benefit of this style is that it does the best job of floating a distressed or fatigued diver face up on the surface.
With a horse collar bcd you need to use a crotch strap to keep it from floating up and popping off over your head. You allso need to wear a separate harness for your tanks.
The horse collar bcd is the least comfortable and most complicated to use. That's Probably why better products have been developed and no one uses them anymore.