They wouldn't offer both if they weren't a good solution for different people. Gastric sleeve, in general, results in about 10% less weight loss than bypass, but also has fewer long-term limitations...but I am a sleeve patient who lost every bit of their excess weight and more. In *general*, you hear of less sleeve patients who cannot tolerate certain foods a couple years after the procedure, and bypass patients sometimes end up being unable to tolerate certain things ever again. That being said, I am a sleeve patient, I am 21 months PO and I still don't tolerate apples, potatoes, rice, pasta, certain types of bread, or carbonation very well so I am still actively avoiding them (which, in a way, has helped me stay on track, so I suppose it's a bit of a mixed bag).
I would listen to your doctor's recommendation and make sure you understand their reasoning for making said recommendation. There is a reason both surgeries are as common as they are.