Pipe top is gonna be more ridgid, I have seen some ange iron trailers made with 3/16 that are okay. Most angle iron trailers are 1/8" angle iron and will hold up fine for the small stuff. If you push your trailers to their weight limits often you don't wanna go that route
PigPig you needa strap on those goggles and weld some stake pockets onto the next pipe top you buy!
Still need to be careful buying pipe top trailers, there are a lot of pipe tips that don't have a good frame, yes they are a little more rigid, but often they cut weight where the customer doesn't see it.
I've got stake pockets, I just need to get the correct straps for them, and with the money I have invested in dozens of straps, I don't plan on replacing them anytime soon.
And what MAXIMUM said, still need to put a chain around you're load, if it has wheels, something will fail