I saw no comments about the Patriot system being a drop in unit compared to the ReadyBrake design. If you are planning on towing more than one vehicle, the Patriot system is likely your best choice. If you plan on towing often, many folks find installing a unit like the Patriot to be inconvenient. You have to have a place to store the unit when not in use, and installing one of the units when it's raining or snowing will make you think twice about your decision.
I'm not a fan of surge brakes so I would lean towards the Invisibrake. I had the Invisibrake in my 97 Wrangler for over 100,000 trouble free towing miles. I would have selected it again but I wanted to be able to apply the towed vehicle brakes independent of the towing vehicle so I now use US Gears Unified Tow Brake.
You may ask why I would care about independent use of the towed vehicles brakes and my answer is that I tow on icy roads where a surge brake just doesn't seem like a good idea.