I am no expert, but I agree that a hydraulic sensing brake controller is the most practical and makes the most sense. But the low frequency I tow and a scarce budget I decided to go with a Tekonosha P3.
I have been very happy with it, and it works great for what I need it to. I have the controller in easy reach, if I ever need to activate the manual override. I installed it in place of my ash tray, and it works well and stays out of the way of my large legs.
I would say, whatever you do, stay away from time-delay controllers, if you can afford it, go with a proportional, if you cant justify the added safety, the inertial controllers seem to work for many.
I used time delay controllers on the vehicles this summer, and they worked if you set them up correctly, but watched two others jackknife a load bad because they didn't change the settings from loaded to unloaded. Luckily noone was hurt.