Just as there are many styles of shirts, there are the same for vests. Some are longer than the waist, some are shorter, some have a lot of buttons from neck to collar, and others have three large buttons. They're made from corduroy fabric to canvas to twill to denim to wool to linen. Some will be lined on the inside, some won't, some will have fabric over the stitches to make it cleaner, and some won't. Some may even be selvage while others are not, so you see; there is a massive variety of vests out there to choose from. Again, it all amounts to what you choose to wear. Are you going to need a formal one? Is it for the colder months? Is it a utility vest? Until you determine what the purpose of the vest is for then you cannot properly buy one based on looks.
Vests have become very versatile in recent years with, both, men and women. They are usually worn open or closed, over long sleeve shirts, t-shirts, or no shirt. They've become a fashion accessory to some and a regular article of clothing to others; it all depends on the vest. If you have a denim vest then you can wear a t-shirt underneath for a casual look or you can get a wool vest and wear a long sleeve workshirt underneath for a more working aesthetic. The formal attire is a poet shirt or blouse with a finer weave of wool, linen, or silk with a satin back or Bemberg Back.
So many ideas for vests, so many styles to be worn but it all comes down to what kind of style do you prefer to wear? A work vest can be worn for formal events as long as you know how to wear it, just as a formal vest can be worn for casual events too. It all depends on how you wear it, even women have jumped on the bandwagon of vests because the tapered styles and cinching allows them to give off the illusion of a smaller waist. Grab a shirt and match it with a vest for a day, you'll like what you see.