"Personally, I dislike the electronic controllers, because they under-react
when you jam on the brakes, and over-react when you are just riding the
brakes down a hill."
I bought an electric brake control system from Northern Tools that is great.
It has two adjustments. One was for delay and the other was for intensity.
It takes a little testing initially to get the setup worked out, but if your
load stays about the same it is fine once you set it. It also has a manual
push bar that is analog---the harder you pushed the harder the brakes came
on. You could use this to add a little drag to the trailer on long hills
without touching your car brakes.
I was very satisfied with how it worked.