My very first rides on a young horse are done with halters. I teach them to soft and have a good feel from the ground from the time they start wearing them. Then I put them in a snaffle and once that is mastered I transition to a curb. The main bit I use is a reining bit with curb and snaffle rings, I use that if I am in public (show, group trail rides) and the horse decides wether he will be in curb or snaffle rings which of course I train them in both so they know how to respond to either. At home on the trail I just use halters. The strongest bridle or leadrope you can get is called trust and leadership.
I ride with bridles, hackamores, and even halters. I also ride with this type of bridle that has a snaffle bit and then another pice that goes around one ear, Its kind of weird. And I ride wiht martingales that connect to the girth bridle(chin strap) and withers.
we usually start them in a hackemore but as soon as possible we start them i a smooth snaffle. It realy depends on the horse and what you do with it. You want to use the lightest bit you possibly can and still have control. If you use a light bit there mouth would be softer and more responsive.