I chose the sleeve because of my age, my need to be able to take NSAIDs for migraines, and the success rate I've seen through my research. I had a coworker that had the bypass and he has gained back all the weight he lost and then some. I know there are ways to cheat with the sleeve, but honestly, it is hard to eat too much! I just came back from lunch and my left overs could be another 3 meals!!!
I am physically able to eat sugar without dumping, but my surgeon's plan is to cut out processed sugars, focus my eating on proteins first, and then if there is any room, vegetables, fruit, and lastly other carbs like bread, but ONLY if there is room (and right now there is barely room for protein!) WLS is not a magic pill or miracle. It's a tool you have to use diligently.
My biggest struggle pre-op was giving into my hunger and not being able to control my portions. With the sleeve, I have not yet felt hunger in 2 months (some people do right after surgery, but I am a lucky one that hasn't regained my hunger yet). I also physically cannot eat more than a few ounces at a time. And since I'm not hungry, I am eating to fuel my body.
One major thing I did not like when looking at the bypass option was that my stomach would still be in my body, and there would be no way to scope it for ulcers or cancer. That scared the crud out of me with all my family's history with cancer and my personal history of ulcers.
Ultimately, you need to do your research and make a decision based on your needs and lifestyle. You're the one using the tool after it's all said and done. I would strongly suggest the sleeve, though.