I use 4 strands of 7 mm electric rope hung on treated wood posts that we put in with a post pounder. It was inexpensive, easy to maintain and looks great. My horses all have awesome manes and taiod because they don't rub on the fence. I keep both a lower and an upper strand electrified so they don't ever get close enough to get tangled.
I used to work for a vet who had a pipe rail fence. His brothers horse got cast under the fence and died. Pipe rail is nice, but that bottom rail has to be low to prevent a horse from getting it's legs stuck if they roll near the fence. That would go for any fence as well.