I have PCOS and slow metabolism but I wanted something that had better stats in the long run and RYN has that. Not to say sleeve doesn't since many have been successful on it as well.
But personally given my medical history and plethora of PCOS related side effects, I opted for bypass. Plus chances of revision is also high with sleeve because of reflux issue. And I didn't want take the route of having to have a second surgery if revision was needed. "ONE surgery and that should be the end of it" was my thought process. Hence even after being confused, I finally opted for bypass.
I know many prefer sleeve because of less chances of dumping and malnutrition, so it depends if those look tempting for you. Though there are 70% of by-passers who also don't dump, myself including. I always wanted a weight loss route that didn't restrict my diet (reason why I hated Keto and other carbs restrictive diets, my binge eating always worsened with them). Even then I took my chance with bypass thinking I shall see when I cross the bridge. And fortunately, I don't dump (at least with some of the sugary and fatty foods I have tried till now).
So give consideration to your medical history, your metabolism, stats and pros and cons of each and go with your gut feeling. That's what I did and so far I haven't regretted it *fingers crossed*