X3 on the Readybrake, its all I've ever used or will use.
Just can't beat it, IMO - Costs significantly less than all the others, provides a simple, reliable braking system with no electronics, nothing to have to put in or take out every time you tow, and no need to tap into any part of your vehicles' electrical system or brakes.
And, most anything that can break on it, you can easily repair yourself with parts found at any hardware store for less than $20. Readybrake is the only system that gives you that simplicity.
Oh, and if you ever sell or trade your towed vehicle, you can order a new Readybrake cable for the new vehicle, for just $60. Sooo, Readybrake can be used with multiple vehicles very easily.
If you haven't bought a tow bar yet, you can get ReadyBrake's ReadyBrute Elite tow bar package, that includes both a tow bar AND their Readybrake system all in one package deal, for 'bout the same as you'd pay for just a tow bar from anyone else. That can save you over $1k from what you'd pay for many other systems, including the SMI.
Will and Cheryl
2021 Newmar Baystar 3014 on F53 (7.3 V8) Chassis ("Brook")
2018 Jeep Wrangler JK ("Wilbur")