What do you have your horses started in? I've used both, but I know different disiplines have their own preferences.
Brennen will be using a snaffle on the yearling he's starting, but the one I'm planning on having as my saddle horse for the next few years (I usually ride mares, it'll be nice not to pack a baby around) will be started in a bosal cause he has a bit of an overbite. His back teeth line up, so that's not a big worry, but I haven't started one in a bosal for a lot of years.