There are so many good ones that I'm not sure there is a BEST. So I'll run a list.
If your motor home is a DP with air brakes, and there is room to install it very little is better than the M&G system. This installs between the booster and the master cylinder and thus is immune to vacuum in the booster, In this it is very nearly unique.
Next comes Air Force One, which also uses Motor home air, but is a pedal pusher (I count both pushers and pullers in the same group) It has a vacuum assist pump to maintain vacuum on the booster.
US-Gear Unified Brake Decelerator is an all electric pedal puller.
All of these have very simple hook up, you hook up the break-a-way lead and the power/control/air lead and that's it folks.
here is a new system by Roadmaster,,, Invisible brake, this uses compressed air but it compresses it. Also a pedal puller.. Hook up is even easier.. You plug in your tow lights (Which you had to do anyway) and the break-away cable, there is also an indicator lead you can plug in... Or not. (not needed for operation but nice to know it's there) These both have vacuum assist pumps as well.
NOTE: the electric units do take battery power from the towed, but they also include a way to recharge,, at least up to this point, from here down no towed charge system is included.
Next we have Ready brake, coupled with the Ready brute tow bar, this is a surge brake system, it is affected by vacuum in the booster tank but it automatically adjusts for it so it does not matter that it lacks a booster pump,, The way this works is very simple and nearly foolproof. As the towed presses against the decelerating motor home a system of levers pulls on a cable pulling the brake pedal toward the floor, the harder you brake the motor home the harder the pedal pulls, It pulls ONLY hard enough to slow the towed the same amount as you are slowing the motor home NO HARDER.. Augomaticall compensating for loss of vacuum in the booster.
Again hook up is quick and easy (Two cables)
Finally we have the ones I do not like.. The "Box" systems like Brake Budy, Even Brake and so on. These are boxes usually with built in air compressors and control hardware that fit in the driver's position and push on the pedal. The main advantage is you can quickly move them to a new car. The main DISadvantage is you have to install them EVERY TIME YOU TOW and un-install them to drive.. This gets to be tiresome and I have had folks admit to saying "oh the heck with it, I'm only going a few miles" and of course good old Murphy says that's when you are gonna wish you'd installed it. I am, after all a dedicated believer in Murphy's laws. (OK that's a joke)
Actually.. the amazing thing in in the book Murphy's law and other reasons why things go wrong book two.. One of the collaries (If nothing can go wrong.. It will anyway) is properly attributed to someone with my last name.. yes, I wrote it. How the author of the book figured that out I'll never know.
(Murphy's law went wrong)
But that.. And of course the tendency of the boxes to "Grow legs" when you are driving the towed, and the fact that they eat towed battery power with out a towed-battery charge option (Though you can add that) is why I don't like them.
Home is where I park it!