There are several systems. I do not like the "Brake Buddy" box in the driver's seat for a number of reasons.. They advertise "No installation" but the fact is YOU install it (not a professional) every time you tow.. Unless of course it's a short trip and you say "oh the heck with it" (yes it happenes)
US-Gear Unified brake decelerator is, in my opinion the best **IF** you know how to take advantage of it's features.. This is an electric over hydraulic system and provides a charge to the towed's battery But you can engage the towed brakes without the motor home's or disable the towed's brakes adjust the "Gain" and it is proportional. I know of no other system that flexible. BUT you need to know how to use some of those features and you should not be driving in places you need them . (They come in handy on bad roads)
I think it's M&G for motor homes with air brakes.. IF and I stress IF it fits your towed it's totally transparent. NOTHIGN in the cockpit (All under the hood) They also make a kit with a 12 volt compressor for Motor homes without air brakes.
Beyond that Ready Break. this is a surge brake system.. if the car "pushes" against the motor home it pulls the brake pedal.. Now there are a couple issues.. One is the cable is a parking brake type cable and if it gets rusty it can jam up on you. Otherwise it's a great system.
Most of the others are enough alike in how well they work as to not distinguish.