I agree with spirit horse that a searching for the perfect bit is not the answer.
If you feel like you need the perfect bit to "control" your horse then you need to focus on establishing communication and leadership with your horse instead.
I would start on the ground first, doing lunging exercises where you ask the horse to constantly change from walk to trot and canter. Also ask him to change direction frequently. Here's an example:
Start having horse Going left:
- Twice around at a walk
- Once around at a trot
- Drop down to walk, one more time around
- Ask to change direction, so horse walking to the right
- Go up to canter, go twice around
- Drop down to trot, once around
- Back up to canter
- Drop to trot, walk, then complete stop
The idea is to be mixing it up to get your horse paying attention and to increase his attention span.
In the saddle, do some exercises to increase his attention span as well. Just go out for leisurely riding and mix things up the same way. John Lyons says you can see when your horse stops paying attention when his ears aren't pointed back focused on you. When you see the horse turning his attention away from you, then ask for a change from what he was doing previously (walk to trot, whatever).
What this does is get your horse listening to you more.