I don't believe there is a perfect supplemental braking system out there. Everybody has their own idea what is best being it simple or complicated with bells and whistles. What works best for you will be based on a how often you plan on towing (note the Brake Buddy comments above), what road conditions do you expect to tow in, and how deep your pockets are.
We've towed a Jeep Wrangler of one sort or another over 100K miles and have had three different brake systems. We started with an air activated system when we a class A DP with air brakes, but when we downsized to a 23' class C, we switched to a Roadmaster Invisibrake. This system is great and it's only shortfall in my opinion is its inability to control the towed vehicles brakes independently.
When we got our new Wrangler last year, I installed US Gear's Unified Tow Brake. If you are interested, you can read my review...
Unified Tow Brake (UTB) Review