I have realized that I am very much biased towards riding horses in snaffle bits. I firmly believe most horses can and should be ridden in one and find them to be effective and useful for all types of training and disciplines. I especially like the eggbut snaffle for older horses and full cheek snaffle for younger horses. Even if a horse is hard mouthed I would rather school them in snaffles until they re-learn to respond to cues. The reason I like them so much is I believe that they are simple and effective yet aren't too harsh for the horse.
Granted, my background is English riding (eventing, dressage, SJ) so I limit my comments to those areas as that is where my experience lays.
So what is your favourite bit and why?