Depends. Bypass is ideal for patients with severe gastric reflux or severe obesity or bad diabetes. Sleeve is great for moderate diabetes and mild reflux. Band is ok for thinner patients (bmi < 40) who have minimal reflux, no diabetes, and good eating habits. Duodenal switch still too much malabsorption.
There is non. Each type of weightless surgery has there own risks and benefits. In general, the better the weight loss, the higher the risk of complications.