I am new to this site, have designed brake controllers for some years now, and you may want to consider a DirecLink unit that plugs into the OBDII connector of your tow vehicle. If monitors vehicle information, far more accurate and responsive then other systems, and has many other features if you ever decide to instally electro-hydraulic brake system on your trailer, and optionally an ABS system.
Ya, the disc brake / abs system isn't cheap, but it does stop if that's your goal. Just in interest of full disclosure I am somewhat biased as I know how they all work, and their limitations. The DirecLink unit is NOT cheap, so if you want to spend only $100 or so don't even look at it. When connected to their hydraulic brake system DirecLink turns the blue wire that actually controls your brakes into a diagnostic and control network, thus provides you all kinds of information relative to the operation of the hydraulic trailer brakes and abs system, if so equipped. If connected to electric brakes, it effectively does the same stuff as the other brake controllers that check for "continuity" and indicate connected or not, as well as current flow and such. The nice thing is it changes operational modes based upon vehicle information and most are quite happy with them. Just verify it supports your vehcile network before buying. Good luck with making your choice as from what I have seen elsewhere, it is quite the emotional activity. If interested I tell people to just do a search on "DirecLink" and "youtube" and you can watch some videos. I wouldn't have jumped in here, but was surprised it wasn't even mentioned.
Would be nice if someone did some independent testing and comparisons, kind of a consumer reports of brake controllers.