Technically speaking, all of those mentioned systems are "branded" versions of a system manufactured by Shenzhen Jetson Electronic Technologies Co., Ltd. None of the companies have a "lock" on the product. Daryl has the Tire Traker brand, Julian has the HawksHead brand, and the Tire Minder brand is available thru Camping World. There are actually several other brands not commonly found in the US. (www.alibaba.com is the place to find out where just about anything comes from...)
That being said, I have been using the HawksHead branded system for 18 months or so without any problems. In fact, it alerted me to a leaking tire on my box trailer on I-80 on our very first trip with it installed. When I tow my Jeep Liberty behind our 41' Overland, it works like a champ without any signal booster. When I tow the 25' trailer, I did experience some signal dropouts, so I put a battery powered repeater in the bedroom of the motorhome.
The Hawkshead system is available at very competitive prices at www.bestrvstuff.com