I use a Blue Ox They make basically 3 good tow bars and a few cheap ones. The good ones are an aluminum one with a 5,000 lb capacity, and two steel ones with 10,000 lb capaciteies, I choose the less expensive steel one (The more expensive steel one was not an option at the time)
One tihng I've not seen mentioned here is BRAKES. I use the Unified Gear system myself, There are several other systems you can also buy, Some are easy to install, some require professional instalation
Advantages of the Unified gear and M&G systems,
NOTHING for the driver to install/remove when towing/driving the car, No pedal pushing anything
Additional advantages of the Unifird Gear system: Proportional braking (You can adjust the application of the towed brakes so it's less than 100%) and progressive (THe harder your brake, the harder it brakes your towed)
Other systems such as the Even Brake and Brake buddy consist of a box you install in the car when towing, and remove when not towing. I opted not to forget this item when towing and use the driver transparent Unified Gear box (US Gear)
http://www.usgear.com/unified_tow_brake.htm
for information on the system I use
Now, do understand thisl.. Towed braking systems are swear things. Folks either swear by them or at them and different people swear differently depending on the system