I have towed with a Blue Ox Aventa for the past 65,000 miles. Most tow bars have a life span of about 75K so mine may need to be replaced in the near future and when I do so, I'll be replacing it with a Roadmaster Sterling All-Terrain.
Through experience, we have found how to avoid serious binding that makes disconnecting a challenge. Typically, it takes two people to disconnect as one has to sit in the vehicle and turn the steering wheel side to side to eliminate the bind. The folks from Roadmaster say the Sterling All-Terrain does not have this binding issue. In addition, the Sterling All-Terrain is aluminum which results in a lower weight and easier handling. One last thing I like about the Sterling All-Terrain is the enclosed cables. This looks better and eliminates some of the issues caused by exposed cables hanging between the vehicles.
I looked on craigslist and found this setup today. $500 for the whole mess. Looks lightly used. Owner said one trip. Doesn't really matter. It's in good shape.
My kit is coming together. Waiting on the bumper. I still need to figure out brakes and lights
Be aware that your Blue Ox tow bar should be serviced every 10,000 miles. This service includes disassembly, cleaning, and re-lubrication plus the replacement of certain nylon washers and o-rings. You can purchase a kit from Blue-Ox and do it yourself or you can have the Blue-ox folks do it for you ($35) at most large RV rallies. We had our done each year at the Quartzsite RV Show while out enjoying the south-western Arizona desert.
I am also new to flat towing, but recently completed our setup and have done a couple trips and just over 1400 miles and am happy with it. Just my personal opinion, but a towbar setup is not something I wanted to buy used with both mechanical and electrical critical components.
I got the Blue Ox Ascent tow-bar because of the non-binding latches (very important as Ron noted) and light weight. There are basically only 3 companies that make this caliber of towing products with Blue Ox and Roadmaster being the better known. I would probably have been happy with a similar tow-bar from RM, but I went with the Maximus-3 tow loops instead of a towing base plate and there are no adapters to marry the RM to the Maximus-3's. BO's customer service has been excellent, too, as I had an issue and they corrected it super fast. For more general towing info, google "dinghy towing guide" as a new one is issued each year.
FWIW, I've both read and heard to avoid using chains as the safety connections as shown in your pic. The BO tow-bars come with rated, coated safety cables and you can also buy them separately. I use a RM 6 to 7 pin umbilical (red!) and the breakaway cable (light orange cable in my pic) came with my RVi Brake system, so don't forgot that item. We're very happy with the RVi Brake 3 (watch their videos) and the Cooltech wiring harness for the signal lights - very quick, easy to connect and disconnect each time you tow.