I use a Dr. Cook's bitless. I got a free one a few years ago, and last year I tried it on my mare. She stops a lot easier with it (not this way with all horses), bends nicer, and doesn't toss her head that much. She is an OTTB.

In a "normal" horse, I still use a bit, but my mare just loves the Dr. Cook's bridle. I don't use the bit because she obviously hates it. I don't think all horses hate bits, but mine does.

I ride with a bit once a month or so just so that she doesn't forget how to go with a bit.