I believe a bit less bridle focuses pressure on the nose while a hackamore uses nose, chin and poll pressure. my mare goes in a hackamore but it is a bit much for her, so I plan to get her a bb. I only recommend hackamores for horses that are stron, but won't accept bit pressure and run through bbs. they can be quite helpful.
I think it really depends on the horse, you should try both and see which one is better for you and the horse... Personally I prefer the BB 😌
I prefer the hackamore, but I know that the BB is better
(rispondo in italiano? ahahahha)