It looks like Tekonsha is the leader.

I've been doing some looking and it appears that if you can hook into the tow vehicle’s brake line that is the way to go. One post I found spelled it out very well. It was long and detailed but the guy basically said: The timed ones suck, the pendulum ones are better and the old style brake line ones are the best but are not made anymore because of anti-lock brakes. The convincing argument for me between the pendulum and the brake line style was that on ice or slippery conditions if the car is not slowing the trailer is not braking. This would also hold true for a very heavy trailer that kept pushing the car during a stop.

Warner still makes an hydraulically operated controller. I guess this is a case where old technology is better, if you can use it. I imagine the sens-a-brake brake pedal controller would work as good but is close to 10 times the cost.