Our first fiver we bought was a mid priced unit. We travel 6-7 months most years and put in the area of 6-10,000 miles on a year. After about 4 years we were starting to have some problems with the frame and suspension, why our roads and weight put lots of stress on a trailer.
We bought the trailer we have now because the company had a good reputation of building great frames; we added good suspension, tires and brakes. We’ve also added an air hitch to help reduce pounding from the roads.
My suggestion is if you plan to put some miles on is to get a good used one with a good frame and suspension. Either an air pin or air hitch will help a lot.