It is a very personal decision and really depends on the current state of your health, how much weight you need to lose and what you would personally feel good about. The DS is usually reserved for extreme conditions of obesity (BMI 50+) and comorbidities and modifies the GI tract more than the other surgeries. It is sort of a combination of the two. You get a vertical sleeve gastrectomy that makes the stomach smaller, and then the GI tract is modified to pass most of the small intestines. This surgery has the highest amount of risk than the other two, but is still a safe surgery. It also has the highest amount of malabsorption, so diet and vitamin you have to be vigilant about diet and vitamin monitoring.
The VSG was born from the DS, as it is the DS surgery without the bypassing of the small intestine. People can have great success with VSG, but it is usually not recommended if you have a history of acid reflux, and even in patients who don't have acid reflux issues pre-surgery, about 20% of VSG patients do experience some after surgery. I chose the VSG and I'm happy with it. I felt it important to get my GI tract in tact, but if I would have been told that an RNY or DS was the better option, I wouldn't have hesitated to go that direction. As it was, I was given a choice to pick was was right for me, and I chose VSG.
The RNY bypasses the stomach and small portion of the small intestine completely. It has a slightly higher average of weight loss than the VSG and slightly less than DS in most cases. It's has a long track record of success (as does the DS) since they've been around longer than the VSG by itself.
All three surgeries can have an incredible influence on health.
I would talk more with your personal doctor and the surgeon to try to really drill down on the pro and cons and what might be best for you.