Pressure treated wood is not a good idea for roosts -- there is absolutely no reason whatsoever to use it, and it is not so great for chickens to be standing barefoot on p/t stuff for half their lives.
Vinyl would be too slippery.
Paint would be ok but get scratched off fairly soon so really why bother. A well-sanded surface does not catch particularly intransigent poo IME. If you are really concerned, give it a coat of mineral oil or linseed oil or something like that, to seal the pores.
GOod luck, have fun,
Pat