The plastic one will not stand up to goats at all.
In my experience, plastic pipe gets brittle and doesn't last many years in the sun.
Plus the goats can just decide to shred it.
You don't really want them chewing on plastic sheeting, it is one thing that can jam up their intestines pretty quickly.
My goats require 6-8 ft of sturdy fencing.
They can hop over 4 ft sheep fence and climb over 5ft horse fencing.
One of them can climb over 6ft chain link.
One day he went over the fence in the back where there were a couple big playful dogs. It panicked him a bit.
So I started over the fence to help him. While I was on top, sort of straddling it, he jumped in my lap.
They had been contained with a wooden slat fence on one side for nearly a year, then one day they decided to knock it all down.
They can push over fencing built with those poles you pound in the ground.
They can tear the welds in garden fencing.
On the other hand, they generally don't try to get out if they are well fed. I currently have them in 5ft temporary horse fence and have not had problems.
I put them in angling about 15 degrees which seems to discourage them from trying to stand up on them.
At my old place, the guy across the street came over just laughing at my goats.
They had been just hopping my fence shortly after I left, and hopping back in before I came home.
At my new place, when we first moved in, one of the goats kept getting out. So I sat and watched from the window. He had found a place in the fence where he had broken the welds.
He would wait until the other goats weren't looking, then dash through.
When we first got them at ten weeks old, my daughter wanted to put a tunnel under the fence so the ducks could get through.
We put a 14" duct in the ground that sloped down under the fence, turned a right angle, then sloped up the other side.
First the ducks just walked through the fence and didn't need a tunnel. Then one of the goats actually squeezed through the duct to escape.
I am not so sure what I would do for a portable paddock. When I do tie them I use a low line instead of a highline so that if they do get tangled, at least they're not dangling.