Before you accuse me of being needlessly violent, let me tell you that a choker is a type of necklace that fits closely around the neck, sort of like a collar, not a method of strangling. Chokers, if worn on the right neck, can be very beautiful, and complement the wearer very well.
Really, the only people that can wear chokers are those with long, thin necks (“swan necks”). As chokers are normally thin, and directly encircle the neck, they tend to make the neck look a little wider than it really is. That said, it would not look very good on a person with a short and/or thick neck, as it would make the neck seem a little thicker, possibly even fat.
For those of you with strong or short necks, the best choice would be a necklace with a very long chain, tapering downwards. As the top of the chain would be touching directly against the neck, the line along the chain seems to follow along the outline of the neck, and makes the neck appear much thinner than it is.