I would use tree limbs (without mites) or wood poles or 2 x 4 s. treated wood may not be your best choice either. Metal will get hot or cold and can damage feet. PVC is okay but slippery and sometimes they like to use perch to clean their beak. Keep various sizes available for flexibility in leg muscles and in case of injury. I change out perches pretty often just to break the patterns of monotony. Keeps it fresh and interesting.
I tried a 2x1 and they wouldn't touch it. I put in a 1x 6 and they roost on it but still hang their toes off the edge it seems which makes for a messy board. Might try and cut it in half or try and find a good tree branch to try.
if it's cold in your area many say to use a 2x4 & lay it flat
that way they can roost with their legs laying more flat
this helps em cover their feet with their breast feathers
so you don't have birds with frostbite on their feet if it gets bitter cold
We also built the ladder type roosts. We have 3 levels which makes it easier for our bigger gals, the Cochin and jersey giant, to get up to the higher ones. We realized we should have spaced them a little farther apart since the ones on the top are pooping on the girls on the lower roosts. . What a mess, hubby is working on new roosts this week.
The best, IMHO, is 2x4's, laid flat so they can cover their feet in the winter. Too small, 2x1's will be uncomfortable on their feet, round they can't grip, and again be uncomfortable on their feet. Yes, tree branches work because of their different widths, they can find what is comfortable for them. I have my roosts removable so I can take them out easily and wash them down when needed, and dry them in the sun.