I flipped back and forth between the two, until I met my surgeon. He asked about my eating habits, and said I was fine for a sleeve or a bypass and (partially due to previous open surgery to have my gall bladder removed years ago) suggested a sleeve, but said the decision was ultimately mine.
I chose a sleeve, and haven't looked back since!
Talk with your surgeon and decide from there - but do your research before so you can ask questions that are important to your decision!