Hi,
All tow-bars for modern cars are type approved - so all makes of tow-bar should have the mounting points in identical positions.
What sets each tow-bar and each manufacturer apart is the quality of the steel used, the design and fabrication techniques used, and the quality of the corrosion protection.
Cheaper prices may not mean poor quality, but in a tow-bar it's difficult to see where cost savings can be made...
Robert