Which is better, to covert a gastric sleeve into a dueodenal switch or to a gastric bypass?

Neither: Iy is my opinion that if you had a sleeve gastrectomy for morbid obesity, and it didn't work, there is not a reasonable expectation that another procedure will work. The operation is only one tool in a box that also must contain dietary modification and some calorie restriction, along with an exercise program and and a perspective that these changes are sustainable for the rest of your life.

Bypass or switch: Duodenal switch with biliopancreatic diversion (dsbpd) is done far less frequently than gastric bypass in the us. It tends to cause excessive malnutrition which is why gastric bypass (lrygb) is preferred and is the most commonly performed operation. I have had to reverse dsbpd patients who were malnourished and have never had to do that with bypass patients. I would recommend gastric bypass.