I use whatever's available. I've made some out of titanium alloy for myself and for others, but they are a little hefty compared to the hollow stainless steel models you can buy everywhere. I also had a very precise pair made of transparent plastic that were nice, and although I've accumulated quite a few wooden and bamboo sets (disposable and non), I prefer using plastic and metal for better durability and ease of washing (scrubbing the hell out of them under hot water). The downside is reduced friction most of the time...bamboo and wood chopsticks often do a better job of holding slippery noodles. Texturing can level the playing field some.
my favorite ones are ceramic. but they break easy.
I have 2 pairs made made from exotic wood from Thailand and 1 pair made in Japan, resin-pressure treated bamboo, able to withstand high temperature and won't rot to water. These are for collection only. Picture later.