I prefer Lyrca , some shows will mandate what material and cut you can wear. I've even been in a show that required black trunk for prejudging only , your night routine could be any color just no stones or decorations.
It looks pretty gay for a grown man to be all oiled up, on stage in tiny "posing trunks" no matter what....but, somehow, those velvet ones are even worse!
They just look really feminine to me.
To each his own.